JP2008251220A - Backlight unit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight unit in which difference of luminance on the surface is reduced by arranging an LED in an appropriate position, and a display device using this. <P>SOLUTION: The liquid crystal display device 1 has a backlight unit 3 which is provided with a holder 8, a light guide plate 9 installed inside the holder 8, and a flexible board 11 on which the LED 10 is mounted. The holder 8 has an LED housing frame 15 provided with a recessed part 14 which is open on the side of the light guide plate 9 and houses the LED 10. The recessed part 14 is formed in a size to restrict movement of the LED 10 housed in it. Light emitted from the LED 10 housed in the recessed part 14 is introduced into the light guide plate 9 from the side face 9a of the light guide plate 9, and thereafter emitted from one of the main surface of the light guide plate 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a backlight unit and a display device.

  In recent years, a liquid crystal display device has a relatively simple structure, can be easily reduced in thickness and weight by selecting constituent members, and can be driven at a low voltage. It is actively used for TVs, video cameras, and vehicle instrument panels.

  For example, in a transmissive liquid crystal display device, a very thin liquid crystal layer of about several μm oriented in a predetermined direction, a pair of transparent thin substrates that sandwich the liquid crystal layer, and a polarizer and A pair of polarizing plates constituting the analyzer. Wiring patterned in a predetermined shape is formed on the substrate surface on the side where the liquid crystal layer is provided. When a voltage is applied to the liquid crystal layer through this wiring, the alignment of the liquid crystal changes, and the amount or wavelength of light transmitted through the liquid crystal layer changes. In the liquid crystal display device, desired display is performed using this.

  In such a liquid crystal display device, generally, a backlight unit is provided on the back side of the liquid crystal layer, that is, on the non-viewing side. There are two types of backlight units, a sidelight type and a direct type, but the sidelight type is often used because it is advantageous in terms of thinning and heat countermeasures.

  Patent Document 1 discloses a conventional liquid crystal display device. The liquid crystal display device includes a liquid crystal display panel, a flexible substrate, and a sidelight type backlight unit. One end of the flexible substrate is connected to the terminal portion of the liquid crystal display panel, and the other end is connected to the control circuit substrate. And it fixes in the state bent by the lower surface side of the backlight unit.

  An LED, which is a chip-type light emitting diode, is mounted on one surface of the flexible substrate. Further, an LED storage portion is provided in the holder of the backlight unit. Then, when the flexible substrate is bent to the lower surface side of the backlight unit, the LED is housed in the LED housing portion. A light guide plate is provided in the holder, and the LEDs housed in the LED housing portion are arranged on the side of the light guide plate.

Japanese Patent Laid-Open No. 2004-177876

  However, in the liquid crystal display device described in Patent Document 1, it is difficult to confirm whether or not the LED is stored in a predetermined position in the LED storage unit. If the LED is not disposed at an appropriate position, the light emitted from the LED is unevenly incident on the inside of the light guide plate, and the luminance difference in the backlight unit surface becomes large. Will result.

  The present invention has been made in view of these points. That is, an object of the present invention is to provide a backlight unit in which an in-plane luminance difference is reduced by arranging LEDs at appropriate positions.

  Another object of the present invention is to provide a display device in which luminance unevenness is improved by using the above backlight unit.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention includes a holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder has a light source storage frame that is connected to a side surface of the holder and has a recess that opens to the light guide plate side and stores the light source.
The recess is sized to limit the movement of the light source housed therein,
The light emitted from the light source accommodated in the recess is introduced from the side surface of the light guide plate into the light guide plate and then emitted from one main surface of the light guide plate. .

In the first aspect of the present invention, the light source storage frame has a protrusion in the vicinity of the recess,
The flexible substrate is provided with an opening,
When the light source is housed in the recess, the protrusion is preferably configured to fit into the opening.

A second aspect of the present invention includes a holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder is a U-shaped opening on the light guide plate side, and has a light source storage frame for storing the light source,
The light source storage frame is sized to limit the movement of the light source stored therein,
The light emitted from the light source housed in the light source housing frame is introduced from the side surface of the light guide plate into the light guide plate and then emitted from one main surface of the light guide plate. It is.

In the second aspect of the present invention, the holder has a protrusion in the vicinity of the light source storage frame,
The flexible substrate is provided with an opening,
When the light source is stored in the light source storage frame, it is preferable that the protrusion is configured to fit into the opening.

A third aspect of the present invention includes a holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder has a light source storage frame provided with a partition wall that is separated from the side surface of the holder and stores a light source between the side surfaces of the light guide plate and restricts movement of the light source,
The light emitted from the light source housed in the light source housing frame is introduced from the side surface of the light guide plate into the light guide plate and then emitted from one main surface of the light guide plate. It is.

In the third aspect of the present invention, the light source storage frame has a protrusion between a side surface of the holder and the partition wall,
The flexible substrate is provided with an opening,
When the light source is stored in the light source storage frame, it is preferable that the protrusion is configured to fit into the opening.

A fourth aspect of the present invention includes a display panel,
A display unit having a backlight unit disposed on a back surface of the display panel and connected to the display panel,
The backlight unit is the backlight unit according to the first aspect, the second aspect, or the third aspect described above.

  According to the first aspect of the present invention, the holder has a light source storage frame that is connected to the side surface thereof and has a recess that opens to the light guide plate side and stores the light source. Since the size of the light source accommodated therein is limited, the backlight unit can be provided in which the LED is arranged at an appropriate position to reduce the in-plane luminance difference.

  According to the second aspect of the present invention, the holder has a U-shape that opens toward the light guide plate, and has a light source storage frame that stores the light source, and the light source storage frame is contained therein. Since the size of the stored light source is limited, a backlight unit is provided in which LEDs are arranged at appropriate positions to reduce the in-plane luminance difference.

  According to the third aspect of the present invention, the holder has a light source storage frame provided with a partition wall portion separated on its side surface, and the light source storage frame is between the side surface of the light guide plate. Since the movement of the housed light source is limited, a backlight unit is provided in which LEDs are arranged at appropriate positions with respect to the side surface of the light guide plate, and the luminance difference in the surface is reduced.

  According to the fourth aspect of the present invention, a display device with improved luminance unevenness is provided.

  FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present embodiment.

  As shown in FIG. 1, the liquid crystal display device 1 includes a liquid crystal display panel 2 and a backlight unit 3 disposed on the back surface of the liquid crystal display panel 2 and connected to the liquid crystal display panel 2. Here, the backlight unit 3 is a sidelight type backlight unit.

  In the liquid crystal display panel 2, a liquid crystal layer (not shown) is sandwiched between a pair of transparent substrates 4 and 5. In addition, a pair of polarizing plates 6 and 7 are attached to these substrates.

  A backlight unit 3 is provided on the back side of the liquid crystal display panel 2, that is, at a position facing the polarizing plate 7 on the anti-viewing side. The backlight unit 3 includes a holder 8, a light guide plate 9 provided inside the holder 8, and a flexible substrate 11 on which an LED 10 as a light source is mounted.

  The holder 8 can have a shape including a rectangular bottom plate 8a and side plates 8b connected to each side of the bottom plate 8a. The bottom plate 8a forms the bottom surface of the holder 8, and the side plate 8b forms the side surface of the holder 8. In addition to the light guide plate 9, a diffusion plate 12 is accommodated on the viewing side of the light guide plate 9, and a reflection plate 13 is accommodated on the non-viewing side of the light guide plate 9 inside the holder 8.

  The flexible substrate 11 is bent approximately 180 degrees from the lower part of the holder 8 to the upper part along the side plate 8 b of the holder 8. One end 11a is connected to a terminal portion (not shown) of the liquid crystal display panel 2, and the other end (not shown) is connected to a control circuit board (not shown). An LED 10 that is a chip-type light emitting diode is mounted on one surface of the flexible substrate 11. When the flexible substrate 11 is bent, the surface on which the LED 10 is mounted faces the holder 8 side above the holder 8. Be placed. Further, although not shown in detail, an electrode having a predetermined wiring pattern is formed on one surface of the flexible substrate 11, and contact terminals for being inserted into the connectors of the control circuit board are provided.

  FIG. 2 is a schematic plan view of the holder 8. As shown in this figure, the holder 8 is connected to the side plate 8b, and has an LED storage frame 15 provided with a recess 14 that opens to the light guide plate 9 side and stores the LED 10. The LED storage frame is a light source storage frame in the present invention (hereinafter the same in the present embodiment). 2 indicates the position where the light guide plate 9 is provided.

  As shown in FIG. 1, the upper surface of the LED storage frame 15 constitutes substantially the same surface as the upper surface of the side plate 8 b of the holder 8. The LED storage frame 15 is provided with a concave portion 14 opened on the light guide plate 9 side, and the size of the concave portion 14 corresponds to the size of the LED 10. That is, the recess 14 has a size that allows the LED 10 to fit comfortably, but limits the free movement of the LED 10 in the recess 14. For example, if the shape of the concave portion 14 is along the outline of the LED 10, the upper limit of the size of the concave portion 14 is about 10% of the size of the LED 10.

  The LED storage frame 15 can be made of the same material as the holder 8. Thereby, when the holder 8 is formed, the LED storage frame 15 can be formed integrally with the holder 8. 1 and 2, the bottom surface of the LED storage frame 15 is exposed from the recess 14. However, the configuration is not limited to this example, and the bottom surface of the holder 8 may be exposed from the recess 14.

  When the flexible substrate 11 is bent above the holder 8 and the LED 10 is stored in the LED storage frame 15, the LED 10 is disposed at an appropriate position in the holder 8. Then, the light emitted from the LED 10 enters the light guide plate 9 through the side surface 9 a from the emission surface 10 a facing the side surface 9 a of the light guide plate 9. Then, after multiple reflection inside the light guide plate 9, it enters a liquid crystal layer (not shown). More specifically, the light enters the liquid crystal layer through the diffusion plate 12 provided on the viewing side of the light guide plate 9. Further, the light emitted from the light guide plate 9 to the non-viewing side is reflected by the reflection plate 13 and reenters the light guide plate 9.

  Thus, by providing the LED storage frame 15, the LED 10 can be installed at an appropriate position with respect to the light guide plate 9. Accordingly, it is possible to reduce the luminance difference in the surface of the backlight unit 3 by suppressing light from entering the light guide plate 9 nonuniformly.

  In the present embodiment, as shown in FIGS. 1 and 2, the LED storage frame 15 preferably has a protrusion 16 in the vicinity of the recess 14. In this case, the flexible substrate 11 is provided with an opening 17 having a size corresponding to the protrusion 16. When the flexible substrate 11 is bent at the top of the holder 8 and the LED 10 is stored in the LED storage frame 15, the protrusion 16 is fitted into the opening 17. Thereby, since it can prevent that LED10 shifts | deviates inside the recessed part 14, LED10 can be arrange | positioned in a more suitable position with respect to the light-guide plate 9. FIG. In addition, by providing the protruding portion 16, it is possible to suppress the flexible substrate 11 from being peeled off from the holder 8 and floating.

  It is preferable that the upper surface of the projecting portion 16 is set so as not to protrude greatly from the opening portion 17 when the projecting portion 16 is fitted into the opening portion 17. Specifically, the upper surface of the protrusion 16 is formed lower than the surface of the opening 17. Alternatively, the upper surface of the protrusion 16 forms substantially the same surface as the surface of the opening 17, or the upper surface of the protrusion 16 is about 0.1 mm to 0.2 mm or less than the surface of the opening 17. It is preferable to form so that it may become high with the value of. If the protrusion 16 protrudes greatly from the opening 17, there is a risk that a defect such as the protrusion 16 hits the liquid crystal display panel 2.

  If the LED 10 is not housed in the LED housing frame 15 when the flexible substrate 11 is bent, or if the protrusion 16 does not fit into the opening 17, the LED 10 is not mounted at an appropriate position on the flexible substrate 11. It will be. Therefore, if the mounting position of the LED 10 is made appropriate by re-soldering or the like, it is possible to prevent the liquid crystal display device having a large luminance unevenness from being manufactured and to improve the manufacturing yield of the liquid crystal display device. Can do.

  The LED storage frame in the present embodiment may have the shape shown in FIG. In addition, the dotted line part of FIG. 3 has shown the position in which a light-guide plate is provided.

  In FIG. 3, the LED storage frame 21 has a U-shaped partition wall having three sides surrounded by a frame. Here, the U-shaped opening 21a is on the light guide plate side in the same manner as the LED storage frame 15 in FIGS. Further, the upper surface of the LED storage frame 21 is substantially the same height as the upper surface of the side plate 20 b of the holder 20. In FIG. 3, the LED storage frame 21 is a frame that forms a U-shape. However, the present invention is not limited to this example. For example, the holder 20 may have a bottom-up surface in contact with the bottom plate 20a, and a frame may be provided on this surface, or may be in contact with this surface. The frame may be provided.

  The LED storage frame 21 has a size corresponding to the LED. That is, while the LED can be accommodated comfortably, it has a size that restricts the free movement of the LED inside. For example, if the shape of the LED storage frame 21 is along the outline of the LED, the upper limit of the size of the LED storage frame 21 is about 10% of the size of the LED.

  In the liquid crystal display device 1 of FIG. 1, the same effect as described above can be obtained when the LED storage frame 15 is replaced with the LED storage frame 21. This will be described with reference to FIG.

  FIG. 4 is a schematic cross-sectional view of another liquid crystal display device in the present embodiment. In FIG. 4, the parts denoted by the same reference numerals as those in FIGS. 1 and 2 are the same.

  When the flexible substrate 11 is bent at the top of the holder 20 and the LED 10 is stored in the LED storage frame 21, the LED 10 is installed at an appropriate position of the backlight unit 3. Then, the light emitted from the LED 10 enters the light guide plate 9 through the side surface 9 a from the emission surface 10 a facing the side surface 9 a of the light guide plate 9. Then, after multiple reflection inside the light guide plate 9, it enters a liquid crystal layer (not shown). More specifically, the light enters the liquid crystal layer through the diffusion plate 12 provided on the viewing side of the light guide plate 9. Further, the light emitted from the light guide plate 9 to the non-viewing side is reflected by the reflection plate 13 and reenters the light guide plate 9. By arranging the LED 10 at an appropriate position with respect to the light guide plate 9, it is possible to prevent light from entering the light guide plate 9 nonuniformly, and to reduce the luminance difference in the surface of the backlight unit 3. it can.

  As shown in FIGS. 3 and 4, a protrusion 22 is preferably provided in the vicinity of the LED storage frame 21. In this case, as in the example of FIG. 1, if the flexible substrate 11 is provided with an opening 23 having a size corresponding to the protrusion 22, the flexible substrate 11 is bent at the top of the holder 20, and the LED 10 is connected to the LED housing frame 21. The protrusion 22 is fitted into the opening 23 by being housed in the opening 23. Accordingly, the LED 10 can be prevented from being displaced inside the LED storage frame 21, and thus the LED 10 can be disposed at a more appropriate position with respect to the light guide plate 9. In addition, by providing the protruding portion 22, it is possible to suppress the flexible substrate 11 from being peeled off from the holder 20 and floating.

  If the LED 10 is not housed in the LED housing frame 21 when the flexible substrate 11 is bent, or if the protrusion 22 does not fit into the opening 23, the LED 10 is not mounted at an appropriate position on the flexible substrate 11. It will be. Therefore, if the mounting position of the LED 10 is made appropriate by re-soldering or the like, it is possible to prevent the liquid crystal display device having a large luminance unevenness from being manufactured and to improve the manufacturing yield of the liquid crystal display device. Can do.

  It is preferable that the upper surface of the protruding portion 22 is set so as not to protrude greatly from the opening 23 when the protruding portion 22 is fitted into the opening 23. Specifically, the upper surface of the protrusion 22 is formed lower than the surface of the opening 23. Alternatively, the upper surface of the protrusion 22 forms substantially the same surface as the surface of the opening 23, or the upper surface of the protrusion 22 is about 0.1 mm to 0.2 mm or less than the surface of the opening 23. It is preferable to form so that it may become high with the value of. If the protrusion 22 protrudes greatly from the opening 23, there is a possibility that problems such as the protrusion 22 hitting the liquid crystal display panel 2 may occur.

  The LED storage frame 22 and the protrusion 23 can be made of the same material as the holder 20. Thereby, when forming the holder 20, the LED storage frame 22 and the protrusion 23 can be formed integrally with the holder 20.

  As described above, according to the present invention, an LED storage frame having a recess or a U-shaped LED storage frame is provided inside the holder, whereby the LED is installed at an appropriate position of the backlight unit. Is possible. Therefore, it is possible to provide a backlight unit in which the in-plane luminance difference is reduced. Further, by using this backlight unit, a display device with improved luminance unevenness can be obtained.

  In the present invention, it is preferable that the holder is provided with a protrusion, and the flexible substrate is also provided with an opening corresponding to the protrusion. Thereby, when the flexible substrate is bent and the LED is stored in the LED storage frame, the protrusion is fitted into the opening, so that it is possible to prevent the LED from being misaligned inside the LED storage frame. Therefore, it is possible to arrange the LED at a more appropriate position with respect to the light guide plate.

  According to the present invention, when the flexible substrate is bent, if the LED is not housed in the LED housing frame, it can be seen that the LED is not mounted at an appropriate position on the flexible substrate. The same can be seen when the projection does not fit into the opening. Thus, according to the present invention, it can be easily confirmed whether or not the LED is housed in a predetermined position with respect to the light guide plate. Therefore, by correcting the mounting position of the LED to an appropriate one, it is possible to prevent a liquid crystal display device having a large luminance unevenness from being manufactured, and to improve the manufacturing yield of the liquid crystal display device.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the liquid crystal display device is taken as an example. However, the present invention is not limited to this, and any other display device may be used as long as the display device has a display panel and a backlight unit that is disposed on the back surface of the display panel and is connected to the display panel. Also good. By using the backlight unit of the present invention, a display device with improved luminance unevenness can be obtained.

It is an example of the cross-sectional schematic diagram of the liquid crystal display device in this Embodiment. It is a plane schematic diagram of the holder of FIG. It is a plane schematic diagram of the other holder in this Embodiment. It is a cross-sectional schematic diagram of the liquid crystal display device which has the holder of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display panel 3 Backlight unit 4,5 Board | substrate 5,6 Polarizing plate 8,20 Holder 9 Light guide plate 10 LED
DESCRIPTION OF SYMBOLS 11 Flexible substrate 12 Diffusing plate 13 Reflecting plate 14 Recessed part 15,21 LED storage frame 16,22 Protrusion part 17,23 Opening part

Claims (7)

A holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder has a light source storage frame that is connected to a side surface of the holder and has a recess that opens to the light guide plate side and stores the light source.
The recess is sized to limit the movement of the light source housed therein,
A backlight unit characterized in that light emitted from the light source housed in the recess is introduced into the light guide plate from a side surface of the light guide plate and then emitted from one main surface of the light guide plate. . The light source storage frame has a protrusion in the vicinity of the recess,
The flexible substrate is provided with an opening,
The backlight unit according to claim 1, wherein when the light source is housed in the recess, the protrusion is fitted into the opening. A holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder is a U-shaped opening on the light guide plate side, and has a light source storage frame for storing the light source,
The light source storage frame is sized to limit the movement of the light source stored therein,
The light emitted from the light source housed in the light source housing frame is introduced from the side surface of the light guide plate into the light guide plate and then emitted from one main surface of the light guide plate. Light unit. The holder has a protrusion in the vicinity of the light source storage frame,
The flexible substrate is provided with an opening,
The backlight unit according to claim 3, wherein when the light source is stored in the light source storage frame, the protrusion is fitted into the opening. A holder,
A light guide plate provided inside the holder;
In a backlight unit including a flexible substrate on which a light source is mounted,
The holder has a light source storage frame provided with a partition wall that is separated from the side surface of the holder and stores a light source between the side surfaces of the light guide plate and restricts movement of the light source,
The light emitted from the light source housed in the light source housing frame is introduced from the side surface of the light guide plate into the light guide plate and then emitted from one main surface of the light guide plate. Light unit. The light source storage frame has a protrusion between a side surface of the holder and the partition wall,
The flexible substrate is provided with an opening,
The backlight unit according to claim 5, wherein when the light source is stored in the light source storage frame, the protrusion is fitted into the opening. A display panel;
A display unit having a backlight unit disposed on a back surface of the display panel and connected to the display panel,
The said backlight unit is a backlight unit of any one of Claims 1-6, The display apparatus characterized by the above-mentioned.

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