JP2005345628A - Backlight system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the entire main surface of a light transmitting plate emit light brightly, by uniformly guiding the light from a light-emitting diode to the light transmitting plate that is arranged on the back of a liquid crystal display panel. <P>SOLUTION: In the end face of a projection 23 formed on the side end of the light transmission plate 12, a recess 24 is formed, with its inner surface formed into a crimped face 25. A light-emitting diode 37 is arranged in the recess 24 having this crimped face 25, and the light from the light-emitting diode 37 is uniformly introduced into the light-transmitting plate 12, while the light is diffused on the crimped face 25, so that uneven emission on the main surface 22 is eliminated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a backlight device, and in particular, includes a light guide plate made of a transparent or translucent material. A light source is arranged on a side end of the light guide plate, and light from the light source is guided into the light guide plate from its main surface. The present invention relates to a backlight device that emits light.

  As a display device for various electronic devices, a small and easy-to-see liquid crystal display panel having a backlight device is widely used. A liquid crystal display device having a backlight device requires a planar light source that radiates the entire surface of the liquid crystal display panel from the back, and as such a planar light source, a light emitting source composed of a fluorescent lamp or an LED (light emitting diode), In general, the light source is composed of a light guide plate that converts a light beam from the light source into a planar light beam that irradiates the liquid crystal panel. In particular, recently, for the purpose of further miniaturization, thinning, and long life, a backlight device composed of a planar light source using an LED as a light emitting source has been widely adopted.

  For example, Japanese Patent Laid-Open No. 2002-196151 discloses that a plate-like transparent material is used to change the optical path of light emitted from a light-emitting light source disposed opposite to the side surface of the light source, so In the light guide plate that emits illumination light, the side surface of the light guide plate that faces the light source is provided with irregularities, and in order to increase the brightness of the illumination light in the edge light type surface light source, a light source such as an LED is used as the light guide plate. There has been disclosed a light guide plate that improves the point where the brightness of illumination light generated from the light guide plate becomes non-uniform depending on the location when the light guide plates are very close to each other.

  Japanese Patent Application Laid-Open No. 11-339527 discloses a primary light source disposed at an end of a light guide plate and a plurality of protrusions that emit light from the primary light source provided on the surface of the light guide plate to the outside of the light guide plate. The protrusion has a height of 40 μm or more, the height difference of the formed protrusion is 10% or less, and the radius of curvature provided on the end surface of the protrusion is A light-emitting device that is 40 μm or less and relates to a planar light source that can be used for a liquid crystal display device or the like, and particularly capable of emitting light uniformly and with high luminance is disclosed.

  Thus, for example, in a backlight type liquid crystal display panel used in an acoustic device or the like, a light guide plate such as an acrylic resin is used, and a main surface of the light guide plate is formed using a lamp such as an LED from a lateral side end thereof. In the case of adopting a method of emitting light from the entire surface, the lamp irradiation surface facing the lamp of the light guide plate is conventionally a glossy surface, so that there is a disadvantage that uneven light tends to occur near the lamp. Therefore, it is necessary to dispose a considerable distance lamp away from a range overlapping with a liquid crystal display panel that requires light emission from the entire surface. This requires the use of a light guide plate having a protrusion protruding laterally from the corresponding surface of the liquid crystal display panel, which increases the size of the light guide plate, and particularly for the liquid crystal display panel. There is a drawback in that the dimension of the side edge on the side where the light source is arranged increases. Further, when the lamp irradiation surface of the light guide plate is a glossy surface, it is impossible to introduce all the light from the light source into the light guide plate, and the light use efficiency of the light source is reduced.

In the configuration disclosed in Japanese Patent Laid-Open No. 2002-196151, since unevenness is provided on the side end surface facing the light emitting light source, the light diffusion efficiency is improved as compared with the side end surface formed of a glossy surface. However, since the light source is arranged at a position away from the side end face by a predetermined dimension, all the light from the light source cannot be guided to the light guide plate, and the light use efficiency is poor. Is not improved much. In addition, there is a drawback that light unevenness is likely to occur in the vicinity of the side end where light from the lamp is incident.
JP 2002-196151 A JP 11-339527 A JP 11-344707 A

  An object of the present invention is to provide a backlight device that effectively guides light from a light source into a light guide plate, thereby improving light utilization efficiency.

  Another object of the present invention is to provide a backlight device that can reduce the protruding amount of the protruding portion of the portion on the side end side where the light source is disposed, particularly on the side end of the light guide plate.

  Another object of the present invention is to provide a backlight device in which unevenness of the brightness of light does not occur at the side edge of the light guide plate, particularly in the vicinity of the side edge where the light source is arranged. .

  Still another problem of the present invention is that, when used as a backlight device for a liquid crystal display panel, the projection of the light guide plate at a portion where the light source is disposed on the side of the side corresponding to the side edge of the liquid crystal display panel. It is an object of the present invention to provide a backlight device in which the size of the portion is further reduced, and thereby the miniaturization of the liquid crystal display device is realized.

  The above-described problems and other problems of the present invention will be clarified by the technical idea of the present invention and the embodiments thereof described below.

A main invention of the present application is provided with a light guide plate made of a transparent or translucent material, a light source is disposed on a side end of the light guide plate, and light from the light source is guided into the light guide plate. In the backlight device that emits light from the surface,
The present invention relates to a backlight device characterized in that a concave portion for receiving the light source is formed at a side end of the light guide plate, the inner surface of the concave portion is subjected to embossing, and the light source is accommodated in the concave portion.

  Here, it is preferable that the light guide plate is disposed on a back side of the liquid crystal display panel, and the concave portion is formed in a protrusion protruding laterally from a position corresponding to a side end of the liquid crystal display panel. The light source is preferably composed of a light emitting diode element. The light source may be a lead type light emitting diode. The embossing applied to the inner surface of the concave portion may be fine irregularities having a depth in the range of 5 to 70 μm. The light guide plate is accommodated in a holder in a state of being superimposed on the back side of the liquid crystal display panel, the holder is mounted on a printed circuit board, and a light source comprising a light emitting diode mounted on the printed circuit board is provided in the holder. It is preferable that the light guide plate is accommodated in the recess through the insertion portion.

  A preferred aspect of the present invention is a case where a light guide plate is used in a backlight type liquid crystal display panel such as an acoustic device, and a light source such as an LED is used from the lateral direction to emit light entirely from the main surface of the light guide plate. In FIG. 5, a concave portion subjected to a treatment having a diffusion effect such as a texture is provided on the lamp irradiation surface of the light guide plate.

  According to such an aspect, in a backlight type liquid crystal display panel such as an acoustic device, when a light guide plate is used and a method of emitting light entirely using a lamp such as an LED from the lateral direction is used, the light guide plate By forming a concave part with a diffusion effect such as embossing on the surface of the lamp, it is possible to eliminate color unevenness in the vicinity of the light source and to deal with main surfaces that require full light emission Accordingly, it is possible to bring the light source closer to the range in which the liquid crystal display panel can be made smaller.

  A main invention of the present application is provided with a light guide plate made of a transparent or translucent material, a light source is disposed on a side end of the light guide plate, light from the light source is guided into the light guide plate, and the main surface of the light guide plate In a backlight device that irradiates light from a light source, a concave portion for receiving a light source is formed at the side edge of the light guide plate, and the inner surface of the concave portion is subjected to embossing so that the light source is accommodated in the concave portion. It is.

  Therefore, according to such a backlight device, the light from the light source disposed in the recess of the light guide plate is diffused widely into the light guide plate from the vicinity of the recess by the unevenness of the texture processed on the inner surface of the recess. For this reason, the unevenness of light in the side end portion where the concave portion for receiving the light source is formed is eliminated. In addition, it is possible to reduce the size of the portion on the side end side where the recess for receiving the light source is formed, and it is possible to reduce the length of the protruding portion on the side end side of the backlight device and to reduce its size. become.

  The present invention will be described below with reference to embodiments shown in the drawings. 1 to 3 show the overall configuration of a liquid crystal display device having a backlight device according to the present embodiment. The liquid crystal display device has a liquid crystal display panel 11 and a light guide plate as shown in FIG. 12, an LCD holder 13, and a printed circuit board 14.

  The liquid crystal display panel 11 has a display surface 17 on the upper surface thereof, excluding the peripheral portion. Further, the liquid crystal display panel 11 is provided with leads 18 parallel to each other at the side edges of the glass substrate, and these leads 18 are bent and protrude downward.

Next, the light guide plate 12 disposed on the lower side of the liquid crystal display panel 11 is a molded body of a transparent resin such as acrylic resin or polycarbonate resin. It has become. And the upper surface is the main surface 22 so as to face the inclined surface 21 subjected to the embossing process. The main surface 22 is a mirror surface, and the main surface 22 is a radiation surface that emits light reflected by the inclined surface 21, and constitutes an emission surface of the planar light source. Further, a side end of the light guide plate 12 is a protrusion 23, and a pair of substantially semicircular recesses 24 for receiving a light source to be described later are formed in the protrusion 23. The inner surface of the concave portion 24 is a textured surface 25, and the inner surface of the concave portion 24 diffuses light from the light source and guides it into the light guide plate 12 by fine irregularities. A gate serving as a resin passage at the time of molding is formed between the side edge of the projection 23 of the light guide plate 12 and between the recesses 24. The LCD that receives the liquid crystal display panel 11 and the light guide plate 12 in an overlapped state. The holder 13 is provided with a pair of locking claws 28 at the top thereof, and the side edges of the liquid crystal display panel 11 are pressed by these locking claws 28. Further, protrusions 30 are formed on the side edges of the LCD holder 13, and guide holes 31 are arranged in a row in these protrusions 30 so that the leads 18 of the liquid crystal display panel 11 can be inserted therethrough. The LCD holder 13 is formed with a locking claw 32 so as to protrude downward. These locking claws 32 are locked in locking holes 34 formed in the printed circuit board 14.

  Next, the printed circuit board 14 on which the LCD holder 13 is mounted will be described. The printed circuit board 14 is a circuit board that is slightly larger than the size of the liquid crystal display device as shown in FIGS. The through holes 36 are formed in a row. The through hole 36 penetrates a lead 18 formed to protrude downward from the side edge of the liquid crystal display panel 11 and is soldered to a wiring pattern on the lower surface of the printed board 14. A pair of light emitting diodes 37 is mounted on the printed circuit board 14. These light emitting diodes 37 are LEDs of a lead type, and are inserted into the holder 13 through the insertion portion 38 at the side end of the LCD holder 13, and particularly as shown in FIGS. In addition, the tip end portion is received in the recess 24 of the protrusion 23 at the side end of the light guide plate 12.

  Therefore, according to such a liquid crystal display device, as shown in FIG. 2, when the light emitting diode 37 on the printed circuit board 14 is energized, the light emitting diode 37 is turned on and emits light as shown in FIG. Such light emission makes it possible to guide light from the light emitting diode 37 to almost the entire surface of the light guide plate 12. The light guided into the light guide plate 12 is diffused and reflected by the inclined surface 21 that is textured on the lower surface thereof, thereby changing its direction toward the upper main surface 22, and a portion of the main surface 22. Becomes a planar light source and emits light upward. Therefore, the light guide plate 12 that emits light from the main surface 22 illuminates the back side of the liquid crystal display panel 11, thereby enabling a bright and easy-to-view display. In particular, in the light guide plate 12 of this liquid crystal display device, since the inner surface of the concave portion 24 of the protruding portion 23 at the side end is constituted by the textured surface 25, the light from the light emitting diode 37 is diffused by the textured surface 25. Thus, it is possible to reliably shine almost the entire main surface 22 of the light guide plate 12.

  As described above, this embodiment is made of a transparent or translucent polymer material such as acrylic resin or polycarbonate resin on the back surface of the liquid crystal display panel 11 in the backlight structure of the liquid crystal display panel in electrical products such as acoustic equipment. The liquid crystal display panel 11 is arranged by irradiating light from a light source such as a light emitting diode 37 from the side end of the light guide plate 12 and illuminating the entire main surface 22 on the upper surface of the light guide plate 12. Is illuminated from the back.

  Here, in particular, the light emitting diode 37 of the light guide plate 12 is irradiated with the light emitting diode 37 by forming a concave portion 24 whose inner surface is a textured surface 25 and disposing the light emitting diode 37 in the concave portion 24. The light emitted from the light guide 37 is radiated toward the opposite end face of the light guide plate 12 without unevenness, and the light emission of the light guide plate 12 due to the light emitting diodes 37 is eliminated.

  Here, the texture on the textured surface 25 of the recess 24 in which the light emitting diode 37 is accommodated is preferably a fine unevenness having a depth of 5 to 70 μm. That is, if the unevenness of the textured surface 25 is more than 70 μm, the light diffusion effect by the light emitting diode 37 is reduced and uneven diffusion on the protrusion 23 side occurs. When the diffusion unevenness increases, the amount of protrusion A to the side of the protrusion 23 shown in FIG. 2 must be increased, which prevents the light guide plate 12 from being downsized.

  Moreover, if the unevenness | corrugation of the embossed surface 25 of the said recessed part 24 is made into fine unevenness of 5 micrometers or less, the brightness | luminance of the light from the light emitting diode 37 will fall. That is, the light from the light emitting diode 37 does not reach far away toward the portion opposite to the protrusion 23 of the light guide plate 12, and only the periphery of the recess 24 is emitted.

  The embossing of the concave portion 24 of the light guide plate 12 is a concave / convex processing for making the inner surface of the concave portion 24 uneven, and can be performed by a chemical treatment, for example, a physical processing such as sandblasting. Can also be performed.

  As described above, according to the configuration in which the concave portion 24 is formed in the protruding portion 23 at the side end of the light guide plate 12, and the light emitting diode 37 is accommodated in the concave portion 24 by applying the embossing to the inner surface of the concave portion 24. It is possible to configure a backlight device for the liquid crystal display panel 11 using the LED 37 with leads. It is particularly preferable to use a high-luminance type LED. That is, since the high-brightness type LED has a light straightness, it reaches the side edge opposite to the protrusion 23 of the light guide plate 12, so that the liquid crystal display panel 11 can shine brighter than the diffusion type LED. It becomes possible. Further, since the inner surface of the concave portion 24 for accommodating the light emitting diode 37 is the textured surface 25, the light from the light emitting diode 37 can be easily diffused, so that the dimension A in FIG. 2 can be reduced. Thus, the projection amount of the projection 23 is reduced as compared with the prior art, and thereby the size of the light guide plate 12 in the same direction can be reduced, and the liquid crystal display device can be miniaturized.

  Next, another embodiment will be described with reference to FIGS. In the above embodiment, the recess 24 for receiving the light emitting diode 37 of the light guide plate 12 is opened on the upper and lower surfaces of the light guide plate 12. However, in this embodiment, the recess for receiving the light emitting diode 37 is not opened on the upper and lower surfaces. A pair of substantially hemispherical concave portions 42 are formed on the side surface of the light guide plate 12 and on the end face of the projection 23, and the inner surface of the concave portion 42 is subjected to embossing to house the light emitting diode 37. doing. Moreover, the aluminum foil 43 is bonded to the upper and lower surfaces of the recess 24, and the bonding interface is used as a reflection surface. This prevents light from leaking to the outside from the upper and lower surfaces of the projection 23 of the light guide plate 12. It is intended to use light more effectively. Instead of the aluminum foil 43, the reflective surface may be formed by an aluminum vapor deposition film, silver plating or the like.

  Therefore, according to such a configuration, the light from the light emitting diode 37 is diffused by the textured surface 25 of the hemispherical recess 42 and guided into the light guide plate 12. In addition, the light emitted from the concave portion 42 in the vertical direction of the light guide plate 12 is reflected by the aluminum foils 43 respectively joined to the upper and lower surfaces of the projection 23 of the light guide plate 12 and guided again into the light guide plate 12. The light leaking to the outside is reduced, and the luminance of the planar light source on the main surface 22 of the light guide plate 12 is increased. Therefore, the liquid crystal display panel 11 including the light guide plate 12 made of a brighter planar light source is provided.

  Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical idea of the invention included in the present application. For example, the above embodiment relates to a backlight device used in combination with a liquid crystal display panel, but the present invention can also be used as a backlight device for other display devices. The specific shape of the light guide plate 12 and the coupling structure between the light guide plate 12 and the liquid crystal display panel are not necessarily limited to the illustrated embodiment, and various design changes can be made.

  The present invention is used in combination with a liquid crystal display panel, and can be widely used as a backlight device constituting a planar light source for illuminating the liquid crystal display panel from the back side.

It is a disassembled perspective view which shows the whole structure of a liquid crystal display device. It is a principal part top view which shows the state of the spreading | diffusion of the light from the light emitting diode with respect to the light-guide plate in the liquid crystal display device. It is the sectional view on the AA line in FIG. It is a top view of a light-guide plate. It is a front view of a light-guide plate. It is a left view of a light-guide plate. It is a right view of a light-guide plate. It is a principal part perspective view of the light-guide plate of a modification. It is a principal part expansion longitudinal cross-sectional view of the same light-guide plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Liquid crystal display panel, 12 ... Light guide plate, 13 ... LCD holder, 14 ... Printed circuit board, 17 ... Display surface, 18 ... Lead, 21 ... Inclined surface, 22 ... Main surface, 23 ... ··· Projection, 24 ··· Recessed portion, 25 · · · Textured surface, 28 · · · Locking claw, 30 · · · Projection, 31 · · · Guide hole, 32 · · · Locking claw, 34 · · · Locking hole, 36 ... Through-hole, 37 ... Light-emitting diode, 38 ... Insertion part, 42 ... Hemispherical recess, 43 ... Aluminum foil

Claims (6)

A light guide plate made of a transparent or translucent material is provided, and a light source is arranged on a side end of the light guide plate, light from the light source is guided into the light guide plate, and light is emitted from the main surface of the light guide plate. In the backlight device,
A backlight device characterized in that a concave portion for receiving the light source is formed at a side end of the light guide plate, the inner surface of the concave portion is subjected to a textured process, and the light source is accommodated in the concave portion.   The light guide plate is disposed on a back side of the liquid crystal display panel, and the concave portion is formed in a protrusion protruding laterally from a position corresponding to a side end of the liquid crystal display panel. The backlight device according to 1.   The backlight device according to claim 1, wherein the light source includes a light emitting diode element.   The backlight device according to claim 3, wherein the light source is a lead type light emitting diode.   The backlight device according to claim 1, wherein the embossing applied to the inner surface of the recess is a fine unevenness having a depth of 5 to 70 μm. The light guide plate is stored in a holder in a state of being superimposed on the back side of the liquid crystal display panel, the holder is mounted on a printed circuit board, and a light source including a light emitting diode mounted on the printed circuit board The backlight device according to claim 2, wherein the backlight device is housed in a recess of the light guide plate through an insertion portion.

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