JP2011113870A - Light guide plate, display device, and manufacturing method of light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate in which a plurality of optical paths can be formed without forming grooves, and numerous light sources can be arranged, to provide a display device equipped with the light guide plate, and to provide a manufacturing method of the light guide plate. <P>SOLUTION: By forming reflecting surfaces 41 nearly without a thickness inside a light-transmitting plate 40, dimensions between respective reflecting faces 41 become larger compared with the dimension of LEDs 8b, so that numerous LEDs 8b can be arranged. Moreover, since the number of optical paths increases compared with the case when the optical paths are formed with the grooves, more minute partial control of the brightness of the light emitted from the light-transmitting plate 40 is more finely carried out, and partial control of the brightness in the display panel can be carried out scrupulously. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light guide plate that emits introduced light from one surface, a display device including the light guide plate, and a method of manufacturing the light guide plate.

  Liquid crystal display devices that occupy a small indoor area compared to the size of the display screen are widely used because they can effectively use a limited indoor space. The liquid crystal display device is configured to display an image by irradiating light from a light source accommodated in a rear cabinet onto a liquid crystal display panel that displays an image disposed inside the front cabinet.

  When a plurality of light sources are arranged to face the liquid crystal display panel, the luminance of the light irradiated to the liquid crystal display panel can be partially controlled by controlling the driving of the light source facing a part of the liquid crystal display panel. . In this case, since many light sources are used, there exists a problem that power consumption increases. On the other hand, when the light guide plate is disposed on the rear side of the liquid crystal display panel and the light source disposed on the side of the light guide plate is irradiated to the liquid crystal display panel, the light guide plate is disposed to face the liquid crystal display panel. Compared to the above, the number of light sources can be reduced, and the power consumption can be reduced. However, it is difficult to partially control the luminance of light applied to the liquid crystal display panel.

  Patent Document 1 discloses a liquid crystal display device in which a plurality of grooves are arranged in parallel on one surface of a light guide plate, and light is reflected at a boundary surface with the grooves. In the liquid crystal display device, a plurality of optical paths are formed in the light guide plate with the boundary surface as a partition. Therefore, by controlling the driving of the light source corresponding to the optical path, the luminance of the light irradiated on the liquid crystal display panel can be reduced. It can be partially controlled.

JP 2009-31445 A

  However, the liquid crystal display device described in Patent Document 1 can be arranged when the width of the groove formed in the light guide plate is larger than the size of the light source and the light source is arranged between the grooves. There has been a problem that the number of light sources is greatly limited.

  The present invention has been made in view of such circumstances, and a light guide plate capable of forming a plurality of light paths without forming grooves and arranging a plurality of light sources, a display device including the light guide plate, and the above-mentioned It aims at providing the manufacturing method of a light-guide plate.

  The light guide plate according to the present invention is characterized in that in the light guide plate that emits light introduced into the light transmissive plate from one surface of the light transmissive plate, a reflective surface that reflects light is provided inside the light transmissive plate. .

  In the present invention, by forming the reflection surface inside the light-transmitting plate, the dimension between the reflection surfaces becomes larger than the dimension of the light source, and a large number of light sources can be arranged. In addition, by extending the reflecting surface in an arbitrary direction, it is possible to cope with a design change of the optical path.

  The light guide plate according to the present invention is characterized in that the reflection surface is provided closer to the other surface of the translucent plate.

  In the present invention, it is possible to prevent light from passing between one surface of the light transmitting plate and the reflecting surface inside the light transmitting plate and lowering the luminance in the vicinity of the reflecting surface on the one surface.

  The light guide plate according to the present invention is characterized in that a groove is provided in a portion of the one surface of the translucent plate facing the reflection surface.

  In the present invention, it is prevented that light is emitted from the side surface of the groove and the luminance in the vicinity of the reflecting surface on the one surface is lowered.

  In the light guide plate according to the present invention, the reflection surface extends from one side surface to the other side surface of the translucent plate, and the reflectance of the central portion of the reflection surface is higher than the end portion of the reflection surface. It is characterized by.

  In the present invention, by making the reflectance of the central portion of the reflecting surface higher than that of the end portion, the light introduced from the side surface of the translucent plate is violently reflected at the central portion, and the introduced light is reflected in the central portion. Even if it attenuates at, the luminance of the central portion is substantially the same as that of the end portion.

  A display device according to the present invention includes the above-described light guide plate and a display panel that displays light by transmitting light emitted from the light guide plate.

  In the present invention, the brightness is adjusted for each optical path formed on the light guide plate described above, and a high-definition image is displayed on the display panel.

  The light guide plate manufacturing method according to the present invention includes a light guide plate manufacturing method in which light introduced to a light transmitting plate that transmits light is emitted from one surface of the light transmitting plate, and laser light is applied to a predetermined position of the light transmitting plate. And a step of generating a crack in the translucent plate and a step of changing the predetermined position.

  In the present invention, by concentrating the laser beam, cracks are generated inside the light-transmitting plate to form a reflecting surface, and a number of optical paths are formed in the light-transmitting plate without providing grooves.

  In the present invention, by forming a reflective surface with almost no thickness inside the translucent plate, the size between the reflective surfaces becomes larger than the size of the light source, and a large number of light sources can be arranged. it can. Further, since the number of optical paths is increased as compared with the case where the optical paths are formed by the grooves, the brightness of the display panel can be partially controlled by controlling the brightness of the light source corresponding to each light path. As a result, the contrast of the video displayed on the display panel can be improved, and blurring of the moving image displayed on the display panel can be suppressed.

  In addition, when a plurality of optical paths are formed by grooves, it is necessary to form a plurality of grooves sufficiently deep with respect to the thickness of the light guide plate in order to reflect light reliably. Even if it is not formed, a plurality of optical paths can be formed, so that the strength of the light guide plate is increased as compared with the case where grooves are formed, and there is a risk that the light guide plate may be damaged due to handling during assembly and impact during use. Can be reduced.

  In the present invention, by extending the reflecting surface in an arbitrary direction, a three-dimensional optical path can be formed, and an optical path suitable for the characteristics of the light guide plate can be designed. Can respond.

FIG. 3 is a front view schematically showing a main configuration of the display device according to the first embodiment. It is a cross-sectional view which shows a display apparatus schematically. It is a longitudinal cross-sectional view which shows a display apparatus schematically. It is a schematic diagram which briefly shows a light-guide plate and a light source unit. It is sectional drawing which shows a light-guide plate schematically. It is explanatory drawing explaining the manufacturing method of a light-guide plate. FIG. 10 is a cross-sectional view schematically showing a light guide plate of Modification 1. It is sectional drawing which shows the light guide plate of the modification 2 schematically. It is sectional drawing which shows the light-guide plate of the modification 3 schematically. 6 is a schematic diagram schematically showing a light guide plate and a light source unit of a display device according to Embodiment 2. FIG. 6 is a schematic diagram schematically showing a light guide plate and a light source unit of a display device according to Embodiment 3. FIG. 6 is a schematic diagram schematically showing a light guide plate and a light source unit of a display device according to Embodiment 4. FIG.

(Embodiment 1)
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating a display device according to a first embodiment. FIG. 1 is a front view schematically showing the configuration of the main part of the display device, FIG. 2 is a transverse sectional view schematically showing the display device, and FIG. 3 is a longitudinal sectional view schematically showing the display device.

  In the figure, reference numeral 1 denotes a rectangular display panel having a liquid crystal, and the display panel 1 is configured to display an image by adjusting a light transmittance by controlling a voltage applied to the liquid crystal. The display panel 1 has a peripheral edge sandwiched between a front holding frame 2 and a rear holding frame 3 and is housed in a rectangular frame-shaped front cabinet (not shown). The front cabinet is disposed around the front holding frame 2 and the rear holding frame 3. The front cabinet has a rectangular opening, and the dimensions of the opening correspond to the display panel 1. On the rear side of the display panel 1, a plurality of optical sheets 5 that collect light emitted from a light guide plate 4 described later toward the display panel 1 are provided.

  On the rear side of the optical sheet 5, a diffusion plate 6 that uniformly diffuses the light emitted from the light guide plate 4 is provided. On the rear side of the diffusion plate 6, a light guide plate 4 having a vertical dimension and a horizontal dimension larger than those of the diffusion plate 6 is provided. A shallow plate-shaped cover 9 is provided on the rear side of the light guide plate 4. The vertical and horizontal dimensions of the cover 9 are larger than those of the light guide plate 4, and the light guide plate 4 is supported by the edge portion of the cover 9. A box-shaped rear cabinet (not shown) that engages with the front cabinet is disposed on the rear side of the cover 9, and the rear cabinet accommodates the light guide plate 4 and the cover 9.

  On the left and right sides of the display device, the edge portion of the cover 9 and the rear holding frame 3 are opposed to each other. Reinforcing rods 7 and 7 for reinforcing the display device are separately provided between the edge portion of the cover 9 and the rear holding frame 3, and a light source is provided between the reinforcing rods 7 and 7 and the light guide plate 4. Units 8 and 8 are provided.

  The light source unit 8 includes an elongated substrate 8a facing the side surface of the light guide plate 4, and a plurality of LEDs (Light Emitting Diodes) 8b, 8b,..., 8b implanted in the substrate 8a. The LEDs 8b, 8b,..., 8b are arranged along the substrate 8a and face the side surface of the light guide plate 4. Driving of the light source unit 8 is controlled by a control circuit (not shown).

4 is a schematic view schematically showing the light guide plate and the light source unit, and FIG. 5 is a cross-sectional view schematically showing the light guide plate.
The light guide plate 4 includes a translucent plate 40 that emits light introduced therein from one surface 40a, and a plurality of reflecting surfaces 41 and 41 that are arranged in the translucent plate 40 and extend in the left-right direction (lateral direction). ,... The translucent plate 40 is made of acrylic plastic. One surface 40 a of the light transmitting plate 40 faces the diffusion plate 6, and both side surfaces of the light transmitting plate 40 face the light source units 8, 8. The LEDs 8b of the light source unit 8 are disposed between the reflective surfaces 41 in the vertical direction (longitudinal direction) or between the reflective surface 41 and the upper and lower end surfaces of the translucent plate 40. The other surface 40 b of the translucent plate 40 faces the cover 9.

  The light of the LED 8b is introduced into the inside from the side surface of the translucent plate 40, travels in the lateral direction while reflecting between the reflecting surfaces 41 or the upper and lower end surfaces of the translucent plate 40, and diffuses from the one surface 40a. The plate 6 is irradiated. That is, an optical path is formed between the reflecting surfaces 41 in the vertical direction or between the reflecting surfaces 41 and the upper and lower end surfaces of the translucent plate 40. The light irradiated to the diffusion plate 6 is irradiated to the display panel 1 through the optical sheet 5.

  As shown in FIG. 5A, the reflection surface 41 has almost no thickness and is formed substantially perpendicular to the one surface 40 a of the translucent plate 40. The front-rear width of the reflection surface 41 is substantially the same as the front-rear width of the translucent plate 40. 5B and 5C, the reflection surface 41 may be formed so as to be inclined with respect to the one surface 40a of the translucent plate 40. The light introduced into the translucent plate 40 is reflected by the reflecting surface 41 and is not transmitted through the reflecting surface 41 as shown by the arrow in FIG. Therefore, the luminance of the display panel 1 can be partially adjusted by controlling the driving of the LED 8b corresponding to each optical path.

  For example, the brightness of the portion of the display panel 1 corresponding to the black image can be reduced, and the contrast of the image displayed on the display panel 1 can be clearly expressed. In addition, when displaying a moving image on the display panel 1, the driving of the LED 8b corresponding to each optical path is controlled, and the luminance of each part of the display panel 1 is sequentially controlled according to the movement of the moving image, so that an image without moving image blur is obtained. Can be displayed.

The light guide plate 4 is manufactured by forming a reflective surface 41 on the light transmitting plate 40. FIG. 6 is an explanatory view for explaining a method of manufacturing the light guide plate.
As shown in FIG. 6, the condenser lens 50 and the light transmissive plate 40 are arranged so that the focal point of the condenser lens 50 is located inside the light transmissive plate 40. Then, high-spiral value laser light emitted from an oscillator (not shown), for example, laser light having a wavelength of 532 nm, is collected by the condenser lens 50 and concentrated at a predetermined position inside the light transmitting plate 40. As a result, a dot-shaped crack 41a is generated at a predetermined position where the laser beam is concentrated. Then, the emission of laser light is stopped.

  Next, the oscillator and the condensing lens 50 are moved or the translucent plate 40 is moved so that the position (predetermined position) where the crack 41 a is to be generated coincides with the focal position of the condensing lens 50. Then, laser light is emitted. By repeating these operations, the reflecting surface 41 having a desired shape can be formed inside the translucent plate 40, and the light guide plate 4 can be manufactured. A predetermined interval (for example, 100 μm) is provided between the cracks 41a. The number of cracks 41 a is determined in consideration of internal stress generated in the light transmitting plate 40. The light reaching the crack 41a is reflected in a predetermined direction. In other words, the crack 41a has directivity with respect to light.

  In the display device according to the first embodiment, the reflective surface 41 having almost no thickness is formed inside the translucent plate 40, so that the dimension between the reflective surfaces 41 is larger than the dimension of the LED 8b. A large number of LEDs 8b can be arranged. In addition, since the number of optical paths is increased as compared with the case where the optical paths are formed by the grooves, the brightness of the display panel 1 can be partially controlled by controlling the brightness of the LEDs 8b corresponding to the respective light paths. . Therefore, the contrast of the video displayed on the display panel 1 can be improved, and blurring of the moving image displayed on the display panel 1 can be suppressed.

  Further, when a plurality of optical paths are formed by grooves, it is necessary to form a plurality of grooves sufficiently deep with respect to the thickness of the light guide plate 4 in order to reflect light reliably. The display according to the first embodiment In the apparatus, since a plurality of optical paths can be formed without forming a groove, the strength of the light guide plate 4 is increased as compared with the case where the groove is formed, handling during assembly, impact during use, and the like. Therefore, the possibility that the light guide plate 4 is damaged can be reduced.

  Further, by extending the reflecting surface 41 in an arbitrary direction, a three-dimensional optical path can be formed, and an optical path suitable for the characteristics of the light guide plate 4 can be designed. In addition, it is possible to easily cope with a design change of the optical path.

  Moreover, since the crack 41a is generated inside the light transmitting plate 40 by the condensed laser light to form the reflecting surface 41, a large number of optical paths can be formed in the light transmitting plate 40 without providing grooves. The partial brightness control in the panel 1 can be executed more finely. Further, the brightness can be adjusted for each optical path, and a high-definition image can be displayed on the display panel 1.

  The translucent plate 40 may be configured to emit light introduced into the inside from one surface 40a, and may be configured of a plastic made of polycarbonate resin or cycloolefin resin. Moreover, although the reflective surface 41 is extended in the horizontal direction, the structure extended in the vertical direction may be sufficient. In this case, LED8b is arrange | positioned so that the translucent board 40 may be opposed to the upper-lower-end surface.

Next, a modification of the display device according to Embodiment 1 will be described. FIG. 7 is a cross-sectional view schematically showing the light guide plate of the first modification.
In the first modification, as shown in FIG. 7, the reflecting surface 41 is formed from the other surface 40 b of the light transmitting plate 40 to the front of the one surface 40 a and is located closer to the other surface of the light transmitting plate 40. Therefore, as shown by the arrow in FIG. 7, light can travel between the one surface 40 a and the longitudinal edge of the reflecting surface 41 in the vicinity of the one surface 40 a. By emitting light from a portion of the one surface 40a facing the longitudinal edge of the reflective surface 41, it is possible to prevent a decrease in luminance near the reflective surface 41 and to make the luminance of the display panel 1 uniform. Can do.

FIG. 8 is a cross-sectional view schematically showing the light guide plate of the second modification.
In Modification 2, as shown in FIG. 8, a narrow groove 42 parallel to the reflective surface 41 is formed in a portion of the one surface 40 a of the translucent plate 40 facing the longitudinal edge of the reflective surface 41. ing. The cross-sectional shape of the groove 42 is rectangular. The reflection surface 41 is formed from the other surface 40 b of the translucent plate 40 to the bottom surface of the groove 42. The light introduced into the translucent plate 40 is emitted from the side surface of the groove 42 as shown by the arrow in FIG. 8, so that a decrease in luminance near the reflective surface 41 is prevented, and the luminance of the display panel 1 is reduced. Can be made uniform. The cross-sectional shape of the groove 42 is not limited to a rectangle, but may be a semicircular shape or a V shape.

FIG. 9 is a cross-sectional view schematically showing a light guide plate of Modification 3.
In the third modification, as shown in FIG. 9, a groove 42 parallel to the reflective surface 41 is formed in a portion of the one surface 40 a of the translucent plate 40 that faces the longitudinal edge of the reflective surface 41. The reflection surface 41 is formed from the other surface 40 b of the translucent plate 40 to the front of the bottom surface of the groove 42. The light introduced into the translucent plate 40 is emitted from the side surface of the groove 42 as shown by the arrow in FIG. 9, and passes between the longitudinal edge of the reflective surface 41 and the bottom surface of the groove 42. Since the light is emitted from the bottom surface of the groove 42, the luminance in the vicinity of the reflective surface 41 can be prevented from being lowered, and the luminance of the display panel 1 can be made uniform.

(Embodiment 2)
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating a display device according to a second embodiment. FIG. 10 is a schematic view schematically showing the light guide plate and the light source unit. The reflection surface 41 arranged in parallel in the translucent plate 40 is configured such that the reflectance increases as it approaches the center portion in the lateral direction. Therefore, the light introduced into the translucent plate 40 by the LED 8b is violently reflected as it approaches the central portion. The light introduced into the translucent plate 40 is gradually attenuated and violently reflected as it travels toward the central portion, so that the luminance of the light emitted from the entire surface 40a of the translucent plate 40 is made uniform. be able to.

  Of the configuration of the display device according to the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

(Embodiment 3)
Hereinafter, the present invention will be described in detail with reference to the drawings showing a display device according to a third embodiment. FIG. 11 is a schematic view schematically showing the light guide plate and the light source unit. In the translucent plate 40, reflecting surfaces 41, 41,..., 41 extending in the lateral direction are arranged in parallel. In addition, a reflective surface 41 extending in the vertical direction is provided inside the translucent plate 40, and the reflective surface 41 extending in the horizontal direction and the reflective surface 41 extending in the vertical direction intersect with each other at a substantially right angle.

  As shown in FIG. 11, the optical path is divided by the reflecting surface 41 extending in the horizontal direction and the reflecting surface 41 extending in the vertical direction, and each optical path is controlled by controlling the driving of the LED 8b corresponding to the divided optical path. The brightness of the display panel 1 can be precisely controlled.

  Of the configuration of the display device according to Embodiment 3, the same components as those in Embodiment 1 or 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

(Embodiment 4)
Hereinafter, the present invention will be described in detail with reference to the drawings showing a display device according to a fourth embodiment. FIG. 12 is a schematic view schematically showing the light guide plate and the light source unit. In the translucent plate 40, reflecting surfaces 41, 41,..., 41 extending in the lateral direction are arranged in parallel. In addition, a reflective surface 42 is provided in the translucent plate 40 so as to extend an appropriate length from the left and right side surfaces of the translucent plate 40 and parallel to one surface 40 a of the translucent plate 40.

  As shown in FIG. 12, an optical path having two layers in the front-rear direction in the vicinity of the left and right side surfaces of the translucent plate 40 and one layer in the central portion of the translucent plate 40 is formed inside the translucent plate 40. Yes. The LEDs 8b, 8b,..., 8b are implanted in the substrate 8a so as to be aligned in two rows along the longitudinal direction of the substrate 8a so as to correspond to the two-layer optical path.

  The light introduced into the front layer from the LED 8 b is emitted toward the display panel 1 from the entire one surface 40 a of the translucent plate 40. On the other hand, the light introduced into the rear layer from the LED 8 b is reflected by the reflecting surface 42 in the vicinity of the left and right side surfaces of the light transmitting plate 40 and proceeds to the central portion of the light transmitting plate 40. Then, the light travels forward at the center of the translucent plate 40 and is emitted toward the display panel 1. Therefore, it is possible to prevent the luminance from being lowered at the central portion of the translucent plate 40 and make the luminance uniform on the one surface 40 a of the translucent plate 40.

  In the display device according to the fourth embodiment, the three-dimensional optical path can be easily realized by forming the reflecting surface 42.

  Among the configurations of the display device according to the fourth embodiment, configurations similar to those of the first to third embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

1 Display panel 4 Light guide plate 8 Light source unit 8b LED
40 Translucent plate 40a One side 40b Other side 41, 42 Reflecting surface 41a Crack

Claims (6)

In the light guide plate that emits light introduced into the light transmissive plate from one surface of the light transmissive plate,
A light guide plate comprising a reflective surface for reflecting light inside the light transmissive plate.   The light guide plate according to claim 1, wherein the reflection surface is provided near the other surface of the translucent plate.   3. The light guide plate according to claim 1, wherein a groove is provided in a portion of the one surface of the translucent plate facing the reflection surface. 4. The reflective surface extends from one side of the translucent plate to the other side,
The light guide plate according to any one of claims 1 to 3, wherein a reflectance of a central portion of the reflecting surface is higher than that of an end portion of the reflecting surface.   A display device comprising: the light guide plate according to claim 1; and a display panel that transmits light emitted from the light guide plate and displays an image. In the method of manufacturing a light guide plate that emits light introduced into a light transmissive plate through which light is transmitted from one surface of the light transmissive plate,
Concentrating laser light at a predetermined position of the light transmitting plate to generate a crack in the light transmitting plate;
The method for manufacturing a light guide plate, comprising: changing the predetermined position.

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