JP2015075669A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent display unevenness caused by heat generated from an LED of a backlight unit.SOLUTION: A backlight unit 31 includes: a light guide plate 61; a pedestal base 50; a plurality of light emission diodes 40; and a partition portion 51. The light guide plate 61 includes: a light emission surface opposed to a liquid crystal panel; and a side surface SS located at an edge of the light emission surface and opposed to each of the light emission diodes 40. On the pedestal base 50, the plurality of light emission diodes 40 are disposed apart from one another. The partition portion 51 is made from metal, includes portions located between the light emission diodes 40 on the pedestal base 50, and partly surrounds each of the light emission diodes 40 on the pedestal base 50.

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including a backlight unit having a light emitting diode.

  The liquid crystal display device is a display device using a liquid crystal panel that does not emit light. For this reason, a backlight unit is often provided on the back of the liquid crystal panel. In recent years, a light emitting diode (LED) has been widely used as a light source of a backlight unit. In this case, the heat generated from the LEDs can adversely affect the liquid crystal display device. For this reason, a method for appropriately treating the heat from the LED has been studied.

  According to the example of Unexamined-Japanese-Patent No. 2006-216244 (patent document 1), the heat radiator is being fixed to the mounting surface of the wiring board in which the LED light source was mounted. Specifically, the heat dissipating body in which the through-hole through which each LED light source passes is fixed so as to surround the LED light source with a minimum gap in a manufacturable range.

  According to the example of Unexamined-Japanese-Patent No. 2004-186004 (patent document 2), the LED light source is provided so that heat conduction may be carried out to the metal chassis which accommodates this. The LED light source is mounted on an LED-FPC (flexible printed wiring board) on which wiring for turning on the LED is formed. The LED-FPC is attached to a plastic frame provided between a liquid crystal display element (liquid crystal panel) and an illumination device (backlight unit).

JP 2006-216244 A JP 2004-186004 A

  According to the technique of Patent Document 1 described above, the position of the LED is regulated in the through hole of the heat radiating body, so that when the thermal expansion / shrinkage occurs, both interfere with each other so that the entire backlight unit is easily deformed. As a result, the display of the liquid crystal display device may be uneven.

  According to the technique of Patent Document 2 described above, local heat retention tends to occur in the plastic frame and the liquid crystal panel on the LED-FPC. Due to the local thermal expansion caused by this, the liquid crystal display device can be deformed. As a result, the display of the liquid crystal display device may be uneven.

  The size of the frame portion of the liquid crystal display device is usually required to be as small as possible. In this case, since the distance between the components cannot be increased, heat stays more easily. In addition, when higher display brightness is required, more LEDs are provided, so the amount of heat generated is also increased. In these cases, display unevenness is more likely to occur. Further, when displaying black, the display unevenness is conspicuous. Therefore, when a more faithful display of black is required, further reduction of the display unevenness is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid crystal display device capable of suppressing display unevenness due to heat generation from LEDs of a backlight unit. It is.

  A liquid crystal display device according to one aspect of the present invention includes a liquid crystal panel and a backlight unit that illuminates the liquid crystal panel. The backlight unit includes a pedestal, a plurality of light emitting diodes, a light guide plate, and a partition portion. The plurality of light emitting diodes are arranged on the pedestal so as to be separated from each other. The light guide plate has a light emitting surface facing the liquid crystal panel and a side surface located at the edge of the light emitting surface and facing each of the light emitting diodes. The partition is made of metal. The partition has a portion located between the light emitting diodes on the pedestal, and partially surrounds each of the light emitting diodes on the pedestal. Here, “partially enclosing” means enclosing only partly, in other words, not completely enclosing.

  A liquid crystal display device according to another aspect of the present invention includes a liquid crystal panel and a backlight unit that illuminates the liquid crystal panel. The backlight unit includes a plurality of light emitting diodes and a light guide plate. The plurality of light emitting diodes are arranged with a gap therebetween. The light guide plate has a light emitting surface facing the liquid crystal panel and a side surface located at an edge of the light emitting surface. The side surface is provided with a plurality of concave portions facing each of the light emitting diodes and a convex portion facing the gap.

  A liquid crystal display device according to another aspect of the present invention includes a liquid crystal panel and a backlight unit that illuminates the liquid crystal panel. The backlight unit includes a plurality of light emitting diodes, a light guide plate, and a rear frame. The light guide plate has a light emitting surface facing the liquid crystal panel, a side surface located at the edge of the light emitting surface and facing each of the light emitting diodes, and a back surface opposite to the light emitting surface. The rear frame is made of metal. The rear frame has a back side portion that faces the back surface of the light guide plate and a support portion that faces the side surface of the light guide plate. The support part directly supports each of the light emitting diodes.

  A liquid crystal display device according to another aspect of the present invention includes a liquid crystal panel and a backlight unit that illuminates the liquid crystal panel. The backlight unit includes a plurality of light emitting diodes, a light guide plate, and a translucent resin member. The light guide plate has a light emitting surface facing the liquid crystal panel and a side surface located at the edge of the light emitting surface and facing each of the light emitting diodes. The translucent resin member is for dispersing light from the light emitting diodes, and is provided between each of the light emitting diodes and the side surface of the light guide plate.

  A liquid crystal display device according to another aspect of the present invention includes a liquid crystal panel and a backlight unit that illuminates the liquid crystal panel. The backlight unit includes a plurality of light emitting diodes, a light guide plate, and a pedestal. The light guide plate has a light emitting surface facing the liquid crystal panel and a side surface located at the edge of the light emitting surface and facing each of the light emitting diodes. The pedestal has a support surface that supports each of the light emitting diodes, and an opposite surface opposite to the support surface. Concave and convex shapes are provided on the opposite surface.

  According to the present invention, display unevenness of the liquid crystal display device due to heat generation from the LEDs of the backlight unit can be suppressed.

1 is an exploded perspective view schematically showing a configuration of a liquid crystal display device according to Embodiment 1 of the present invention. It is a schematic sectional drawing in alignment with line II-II of FIG. FIG. 3 is a schematic partial enlarged view of the backlight unit of FIG. 2, and is a view along line III-III of FIG. FIG. 4 is a schematic partial sectional view taken along line IV-IV in FIG. 3. FIG. 4 is a schematic partial plan view (A) of the backlight unit from the viewpoint of an arrow VA in FIG. 3 and a schematic partial cross-sectional view along the line VB-VB. It is a fragmentary sectional view which shows schematically the structure of the liquid crystal display device in Embodiment 2 of this invention, and is a figure in alignment with line VI-VI of FIG. It is a schematic fragmentary sectional view which follows the line VII-VII of FIG. It is a fragmentary sectional view which shows schematically the structure of the liquid crystal display device in Embodiment 3 of this invention. It is a fragmentary sectional view which shows roughly the structure of the liquid crystal display device in Embodiment 4 of this invention. It is a fragmentary sectional view which shows schematically the structure of the liquid crystal display device in Embodiment 5 of this invention. It is a figure which shows the 1st modification of FIG. It is a figure which shows the 2nd modification of FIG. It is a figure which shows the 3rd modification of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
Referring to FIGS. 1 and 2, liquid crystal display device 100 of the present embodiment includes liquid crystal panel 10, backlight unit 31 that illuminates liquid crystal panel 10, and front frame 79. The liquid crystal panel 10 includes a TFT (Thin Film Transistor) array substrate 11, a counter substrate 12, a flexible substrate 13, and a circuit substrate 14. The circuit board 14 is arranged on the back side (the side not shown in FIG. 1) of the backlight unit 31 by bending the flexible board 13 as indicated by the broken line arrows in FIG. In other words, the backlight unit 31 is sandwiched between the liquid crystal panel 10 and the circuit board 14. Liquid crystal is sealed in a gap (not shown) between the TFT array substrate 11 and the counter substrate 12. A circuit substrate 14 is connected to the TFT array substrate 11 via a flexible substrate 13. The display signal generated by the circuit board 14 is input to a drive IC (Integrated Circuit) mounted on the flexible board 13. The driving IC converts the input display signal into a signal having a level and timing suitable for driving the TFT array substrate 11, and outputs the signal to the TFT array substrate 11. On the TFT array substrate 11, TFTs arranged corresponding to the pixels, and gate wirings and source wirings (not shown) for driving the TFTs are provided. The counter substrate 12 may be provided with a color filter for performing color display.

  With reference to FIG. 3 and FIG. 4, the backlight unit 31 includes an LED unit 41, a light guide plate 61, and a rear frame 71.

  The light guide plate 61 has a light emitting surface SE facing the liquid crystal panel 10, a reverse back surface SB, and a side surface SS located at the edge of the light emitting surface SE. Optical sheets 81 and 82 are provided on the back surface SB and the light emitting surface SE of the light guide plate 61, respectively. The optical sheet 81 is, for example, a reflection sheet. The optical sheet 82 is, for example, a laminate of a diffusion sheet, a lens sheet, and the like.

  The LED unit 41 includes a pedestal 50, a plurality of LEDs 40 (light emitting diodes), and a partition 51. The pedestal 50 has a support surface US and an opposite opposite surface UO. The support surface US of the pedestal 50 supports the LED 40 and the partition portion 51. The opposite surface UO of the pedestal 50 is supported by the rear frame 71.

  An LED unit 41 and a light guide plate 61 are housed in the rear frame 71. The rear frame 71 holds the liquid crystal panel 10 (FIG. 2) together with the front frame 79 (FIG. 2).

  Further, referring to FIGS. 5A and 5B, pedestal 50 is a rectangular plate extending in one direction (lateral direction in the figure). A plurality of LEDs 40 are provided on the base 50 along this direction. The plurality of LEDs 40 are arranged apart from each other. The plurality of LEDs 40 are electrically connected in series with each other. Each of the LEDs 40 faces the side surface SS of the light guide plate 61. The partition 51 is made of metal. The partition 51 has a portion located between the LEDs 40 on the pedestal 50, and partially surrounds each of the LEDs 40 on the pedestal 50. Preferably, a gap is provided between the LED 40 and the partition 51, thereby separating them from each other.

  According to the present embodiment, the partition 51 for promoting the diffusion of heat from the LED 40 partially surrounds the LED 40 on the pedestal 50. Thereby, compared with the case where the partition part completely surrounds LED40, the mutual restraint of the partition part 51 and LED40 becomes looser. Therefore, the deformation of the backlight unit 31 due to the difference in thermal expansion and contraction between the two is suppressed. Therefore, display unevenness of the liquid crystal display device 100 due to the deformation of the backlight unit 31 is suppressed.

  Moreover, since the partition part 51 is made from a metal, compared with the case where it is made from resin, such as a polycarbonate, the thermal conductivity of the partition part 51 is improved. Therefore, the diffusion of heat from the LED is further promoted.

(Embodiment 2)
Referring to FIGS. 6 and 7, the liquid crystal display device according to the present embodiment has backlight unit 32 instead of backlight unit 31 (FIGS. 3 and 4) to illuminate liquid crystal panel 10 (FIG. 2). . The backlight unit 32 includes an LED unit 42, a light guide plate 62, and a rear frame 71. The LED unit 42 includes a pedestal 50 and a plurality of LEDs 40. The plurality of LEDs 40 are arranged on the pedestal 50 with a gap therebetween.

  The light guide plate 62 has a light emitting surface SE facing the liquid crystal panel 10 (FIG. 2), a reverse back surface SB, and a side surface SS located at the edge of the light emitting surface SE. Optical sheets 81 and 82 are provided on the back surface SB and the light emitting surface SE, respectively. The side surface SS is provided with a plurality of concave portions PR facing the respective LEDs 40 and convex portions PP facing the gaps between the LEDs 40.

  Since the configuration other than the above is substantially the same as the configuration of liquid crystal display device 100 of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and description thereof is not repeated.

  According to the present embodiment, the side surface SS of the light guide plate 62 is provided with the plurality of concave portions PR facing each of the LEDs 40 and the convex portions PP facing the gaps between the LEDs 40. Thereby, the distance between the side surface SS of the light guide plate 62 and each of the LEDs 40 is made more uniform over the entire side surface SS. Therefore, the amount of heat flowing from the LED 40 to the side surface SS is also made more uniform. Therefore, deformation of the light guide plate 62 due to local thermal expansion is suppressed. Therefore, display unevenness due to the deformation of the backlight unit 32 is suppressed. As described above, display unevenness due to heat generation from the LEDs 40 of the backlight unit 32 can be suppressed.

  Further, as described above, the distance between the side surface SS of the light guide plate 62 and each of the LEDs 40 is made uniform, so that the amount of light incident on the light guide plate 62 can also be made uniform. Thereby, the liquid crystal panel 10 can be illuminated more uniformly. Therefore, display unevenness of the liquid crystal display device can be further suppressed.

  Further, the above-described equalization of the distance between the side surface SS of the light guide plate 62 and each of the LEDs 40 can be performed only by adjusting the shape of the side surface SS without providing any special additional parts. Therefore, this embodiment can be applied without causing a significant increase in manufacturing cost.

  In FIG. 7, a saw-like structure is provided on the side surface SS of the light guide plate 62 by the concave portions PR and the convex portions PP. However, other shapes such as a wave-like structure may be provided.

(Embodiment 3)
Referring to FIG. 8, the liquid crystal display device according to the present embodiment has a backlight unit 33 instead of backlight unit 31 (FIGS. 3 and 4) to illuminate liquid crystal panel 10 (FIG. 2). The backlight unit 33 includes a plurality of LEDs 40, a light guide plate 61, and a rear frame 73. The rear frame 73 is made of metal. The rear frame 73 has a back side portion 73B and a support portion 73S. The back side portion 73B and the support portion 73S are connected to form a right-angled corner. The back side portion 73 </ b> B faces the back surface SB of the light guide plate 61. The support portion 73S faces the side surface SS of the light guide plate 61.

  The support portion 73S of the rear frame 73 directly supports each LED 40. Therefore, in the present embodiment, a dedicated pedestal for making the plurality of LEDs 40 one unit is omitted, and the rear frame 73 also serves as the function. Preferably, the thickness TS of the support portion 73S is larger than the thickness TB of the back side portion 73B. Here, the thickness TS is a dimension along the normal direction (lateral direction in the drawing) of the surface supporting the LED 40, and the thickness TB is the normal direction of the surface supporting the light guide plate 61 (in the drawing). , Along the vertical direction).

  Since the configuration other than the above is substantially the same as the configuration of liquid crystal display device 100 (FIG. 1) of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and the description thereof is repeated. Absent.

  According to the present embodiment, the support portion 73S of the rear frame 73 directly supports each LED 40. Thereby, the heat generated from the LED 40 is directly absorbed by the metal rear frame 73. Therefore, deformation due to thermal expansion of the optical system such as the light guide plate 61, the optical sheets 81 and 82, or the liquid crystal panel 10 is suppressed. Therefore, display unevenness of the liquid crystal display device can be suppressed.

  The rear frame 73 is heated non-uniformly due to the heat generated from the individual LEDs 40. However, if the rear frame 73 is formed of a thermally uniform material, the rear frame 73 is discontinuous in thermal expansion. There is no difference. In this case, the main influence of the thermal expansion of the rear frame 73 on the optical system is only a slight increase in the distance between the LEDs 40, and there is almost no distortion accompanied by twisting that affects the direction of light emitted from the LEDs 40. Not caused. Therefore, the disturbance in the direction of light emitted from the LED 40 is small, and the display unevenness due to the disturbance is small.

  Further, since the thickness TS of the support portion 73S is larger than the thickness TB of the back side portion 73B, the heat capacity, thermal conductivity, and rigidity of the portion of the rear frame 73 to which the LED 40 is attached are increased. Thereby, the deformation | transformation of the rear frame 73 resulting from a thermal expansion is suppressed. Therefore, display unevenness due to deformation of the rear frame 73 is suppressed.

(Embodiment 4)
Referring to FIG. 9, the liquid crystal display device according to the present embodiment has a backlight unit 34 instead of backlight unit 31 (FIGS. 3 and 4) to illuminate liquid crystal panel 10 (FIG. 2). The backlight unit 34 includes an LED unit 44, a light guide plate 61, and a rear frame 71. The LED unit 44 includes a pedestal 50, a plurality of LEDs 40, and a translucent resin member 54. As described in the first embodiment, the light guide plate 61 has the side surface SS facing each of the LEDs 40. The translucent resin member 54 is provided between each LED 40 and the side surface SS of the light guide plate 61. The translucent resin member 54 is for dispersing the light from the LED 40.

  Since the configuration other than the above is substantially the same as the configuration of liquid crystal display device 100 (FIG. 1) of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and the description thereof is repeated. Absent.

  According to the present embodiment, the light from the LED 40 is dispersed by the translucent resin member 54. Thereby, the light guide plate 61 is illuminated more uniformly, and as a result, the liquid crystal panel 10 is illuminated more uniformly. By making the light uniform in this way, the heat distribution due to the loss during the propagation of the light is also made uniform. That is, not only the light is made uniform, but the heat distribution is made uniform accordingly. By making the heat distribution uniform, display unevenness due to deformation of the liquid crystal display device due to thermal expansion can be suppressed.

  When the LED 40 is in contact with the translucent resin member 54, the translucent resin member 54 can directly absorb the heat from the LED 40, so that the translucent resin member 54 not only serves as an optical member but also dissipates heat. It can also act as a member. The translucent resin member 54 may be directly formed on or pasted on the LED 40. If priority is given to suppressing the distortion caused by the difference in thermal expansion and contraction between the two, they may be arranged so that they can be displaced while being in contact with each other, and further, while both are facing each other. They may be spaced apart.

(Embodiment 5)
Referring to FIG. 10, the liquid crystal display device of the present embodiment has a backlight unit 35 instead of backlight unit 31 (FIGS. 3 and 4) to illuminate liquid crystal panel 10 (FIG. 2). The backlight unit 35 includes an LED unit 45, a light guide plate 61, and a rear frame 71. The LED unit 45 includes a plurality of LEDs 40 and a pedestal 55.

  The pedestal 55 has a support surface US that supports each of the LEDs 40 and an opposite surface UO opposite to the support surface US. The opposite surface UO is provided with a wavy uneven shape.

  Since the configuration other than the above is substantially the same as the configuration of liquid crystal display device 100 (FIG. 1) of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and the description thereof is repeated. Absent.

  According to the present embodiment, an uneven shape is provided on the opposite surface UO of the pedestal 55. Thereby, since the area of the opposite surface UO becomes large, the heat dissipation from there is accelerated | stimulated. Thereby, the heat generated from the LED 40 is efficiently diffused. Therefore, deformation of the backlight unit 35 due to thermal expansion is suppressed. Therefore, display unevenness of the liquid crystal display device is suppressed. In particular, when the concave portion of the opposite surface UO of the pedestal 55 is hollow as shown in FIG. 10, heat dissipation by the air cooling action is promoted.

  Next, first to third modifications of the backlight unit 35 will be described below.

  Referring to FIG. 11, a backlight unit 35v as a first modification has an LED unit 45v. The LED unit 45v has a pedestal 55v instead of the pedestal 55 (FIG. 10). On the opposite surface UO of the pedestal 55v, many banks-like thin walls are provided as heat radiation fins. This further enhances the air cooling effect.

  Referring to FIG. 12, a backlight unit 35w as a second modification has a rear frame 71w instead of the rear frame 71 (FIG. 10). The rear frame 71w is provided with an uneven shape that meshes with the uneven shape of the opposite surface UO of the pedestal 55. Thereby, although the air cooling action described above is reduced, the contact area between the pedestal 55 and the rear frame 71w is increased, so that the heat radiation action from the pedestal 55 to the rear frame 71w is promoted. The uneven shape of the rear frame 71w may be formed in advance before the mounting of the pedestal 55, or may be formed by recessing the uneven shape of the pedestal 55 into the rear frame 71w when the pedestal 55 is mounted.

  Referring to FIG. 13, a backlight unit 35x as a third modification has an LED unit 45x. The LED unit 45x has a pedestal 55x instead of the pedestal 55 (FIG. 10). The pedestal 55x has a flat plate portion 55a and a protruding portion 55b. In the present modification, the protrusions 55b are attached on the flat surface of the flat plate portion 55a, so that an uneven shape is provided on the opposite surface UO of the pedestal 55x. It is desirable that the thermal expansion coefficients of the flat plate portion 55a and the protruding portion 55b are approximately the same. The material of the flat plate portion 55a and the protruding portion 55b may be the same.

  In the present embodiment and its modifications, the rear frame and the pedestal may be arranged so that they can be displaced from each other while being in contact with each other. Thereby, the distortion resulting from the difference in thermal expansion and contraction between the rear frame and the pedestal is suppressed.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 10 liquid crystal panel, 100 liquid crystal display device, 11 TFT array substrate, 12 counter substrate, 13 flexible substrate, 14 circuit board, 31-35, 35v-35x backlight unit, 40 LED (light emitting diode), 41, 42, 44, 45, 45v, 45x LED unit, 50, 55, 55v, 55x pedestal, 51 partition part, 54 translucent resin member, 55a flat plate part, 55b protruding part, 61, 62 light guide plate, 71, 71w, 73 rear frame, 73B Back side part, 73S support part, 79 Front frame, 81, 82 Optical sheet, PP convex part, PR concave part, SB back surface, SE light emitting surface, SS side surface, UO opposite surface, US support surface.

Claims (6)

LCD panel,
A backlight unit that illuminates the liquid crystal panel, and the backlight unit includes:
A pedestal,
A plurality of light emitting diodes spaced apart from each other on the pedestal;
A light guide plate having a light emitting surface facing the liquid crystal panel, and a side surface located at an edge of the light emitting surface and facing each of the light emitting diodes;
A liquid crystal display device comprising: a partition made of metal, having a portion located between the light emitting diodes on the pedestal, and partially surrounding each of the light emitting diodes on the pedestal. LCD panel,
A backlight unit that illuminates the liquid crystal panel, and the backlight unit includes:
A plurality of light emitting diodes arranged with a gap between each other;
A light-emitting plate facing the liquid crystal panel, and a light guide plate having a side surface located at an edge of the light-emitting surface, the side surface facing a plurality of recesses facing each of the light-emitting diodes, and the gap A liquid crystal display device provided with a convex portion. LCD panel,
A backlight unit that illuminates the liquid crystal panel, and the backlight unit includes:
A plurality of light emitting diodes;
A light-emitting plate facing the liquid crystal panel, a side surface facing each of the light-emitting diodes located at an edge of the light-emitting surface, and a light guide plate having a back surface opposite to the light-emitting surface;
A rear frame made of metal having a back side portion facing the back surface of the light guide plate and a support portion facing the side surface of the light guide plate, wherein the support portion directly connects each of the light emitting diodes. Supporting liquid crystal display device.   The liquid crystal display device according to claim 3, wherein a thickness of the support portion is larger than a thickness of the back side portion. LCD panel,
A backlight unit that illuminates the liquid crystal panel, and the backlight unit includes:
A plurality of light emitting diodes;
A light guide plate having a light emitting surface facing the liquid crystal panel, and a side surface located at an edge of the light emitting surface and facing each of the light emitting diodes;
A liquid crystal display device, comprising: a translucent resin member for dispersing light from the light emitting diodes provided between each of the light emitting diodes and the side surface of the light guide plate. LCD panel,
A backlight unit that illuminates the liquid crystal panel, and the backlight unit includes:
A plurality of light emitting diodes;
A light guide plate having a light emitting surface facing the liquid crystal panel, and a side surface located at an edge of the light emitting surface and facing each of the light emitting diodes;
A liquid crystal display device comprising: a support surface that supports each of the light emitting diodes; and a pedestal having an opposite surface opposite to the support surface, wherein the opposite surface is provided with an uneven shape.

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