JP4794673B2 - Surface illumination device and liquid crystal display device including the same - Google Patents

Description

  The present invention relates to a surface illumination device using a discrete light source array and a liquid crystal display device including the same.

  The liquid crystal display device is provided with a surface illumination device on the front or rear surface of the liquid crystal display panel. As a backlight unit that is a surface illumination device arranged on the rear surface of the panel, a sidelight (edge light) type in which a light source is arranged on the edge of a light guide plate that guides light, and a light source is arranged directly under the liquid crystal display panel There is a direct type. In general, a cold cathode tube is used as a light source. However, in recent years, environmental issues have been emphasized, and it is not preferable to use a cold cathode tube containing mercury. Accordingly, various light sources such as mercury-free fluorescent tubes and LEDs (light emitting diodes) have been developed as light sources to replace the cold cathode tubes. Among them, LEDs are regarded as promising as the next light source.

  When LED is used as a light source in the sidelight type backlight unit, a configuration in which a plurality of white LEDs are arranged and each single color LED of different emission colors (for example, R (red), G (green), B (blue)) are set. Thus, a configuration in which a plurality of sets are arranged is considered. The white LED is a combination of a yellow light-emitting phosphor and a blue light-emitting LED, and the variation in emission color is relatively small. On the other hand, a backlight unit using a combination of R, G, and B single-color LEDs is extremely advantageous in that it can achieve vast color reproducibility (for example, Adobe-RGB range) that cannot be achieved with white LEDs. Has attracted attention.

  In order to mix emission colors from discrete light source arrays, a method (sub light guide plate method) in which a light guide region that is not used is provided in the display region has been proposed (see Non-Patent Document 1). Since the light incident efficiency from the LED to the sub light guide plate and the light incident efficiency from the sub light guide plate to the main light guide plate are low, there is a problem that the light use efficiency is very low as a whole. If the light utilization efficiency is low, it is necessary to increase the input power, so that it is necessary to take measures against heat, and there is also a problem that the size of the apparatus is increased due to heat radiation fins.

  In order to solve these problems, a backlight unit has been proposed in which an air region having a predetermined thickness is provided between the light guide plate and the diffuser plate to mix light emission colors well. FIG. 30 schematically shows a light guide plate and an LED module used in the proposed backlight unit. As shown in FIG. 30, LED modules 115 are arranged on opposite long side surfaces (light incident surfaces) 112T and 112B of the rectangular light exit surface 116 of the thin light guide plate 110. In order to efficiently use the light from the LED module 115, both side surfaces on the short side of the light guide plate 110 are reflecting surfaces 113L and 113R.

  The number of LEDs 77 of each color in the LED module 115 is determined by the white balance setting. Usually, one B (blue) light emitting LED 77B, R (red) light emitting LED 77R, and G (green) light emitting LED 77G are combined to form one set. By disposing the LEDs 77 of the respective colors at equal intervals, the distance from the light incident surface 112 where the colors of the individual LEDs 77 are visually recognized is substantially the same in any LED 77.

Accordingly, the LED module 115 includes, for example, an end portion on the reflecting surface 113L side, an LED 77G that emits G (green) light from an end portion of the reflecting surface 113L, an LED 77R that emits R (red) light, and an LED 77B that emits B (blue) light. Have an LED set 100 (hereinafter referred to as “GRB” set as necessary) 100 arranged in this order. The LED module 115 includes the “GRB” set 100 as a unit, the “GRB” width as one pitch, the light incident surface 112T of the light guide plate 110,
A plurality of them are arranged in order from the left end of 112B.

  With such a configuration, at an arbitrary point inside the light emitting surface 116, three lights from the G color LED 77G, the R color LED 77R, and the B color LED 77B in the vicinity of the arbitrary point are mixed to obtain a desired color. Can produce light.

  However, at an arbitrary point in the vicinity of the upper surface of the reflecting surface 113L on the left short side of the light exit surface 116, for example, not only the direct light from the “GRB” set 100 on the left end of the light incident surface 112T but also the “GRB” set 100. The light of the mirror image “BRG” set 101 reflected by the reflecting surface 113L also arrives. In other words, in the vicinity of an arbitrary point in the vicinity of the upper portion of the reflecting surface 113L, this is equivalent to one set of six “BRGGRB” LEDs being arranged in order from the left side of the figure, and among them, 4 near the arbitrary point. The light from “RGGR” of the LED sets will be mixed relatively strongly and “B” will not be present at all. For this reason, at the arbitrary point, a mixed white with insufficient blue component is obtained, and there is a problem that yellow color unevenness is likely to occur near the upper end of the reflecting surface 113L. When the same LED arrangement is used, this color unevenness also occurs at the lower end portion of the reflective surface 113L and the upper end portion and lower end portion of the right reflective surface 113R. Further, even if the LED set 100 is changed from the “GRB” pattern to the “GBR” pattern, the same problem occurs.

  In order to avoid this problem, there is a method of removing a portion where color unevenness is generated from the display area, but this is not preferable because the frame area of the display device is enlarged at least about 5 cm in the vertical direction or the horizontal direction. In addition, since a large LED backlight uses 100 or more LEDs, there are variations in the light emission efficiency and light emission wavelength of the LEDs, which cause unevenness in the frame.

JP 2003-215349 A JP 2003-95390 A

Nikkei Electronics, March 31, 2003, no. 844, p126-127

  An object of the present invention is to provide a surface illumination device capable of obtaining good display quality using a discrete light source array and a liquid crystal display device including the same.

  The object is to provide a light emitting area for emitting light distributed in a planar shape, a light guiding area for guiding light to the light emitting area, a light incident surface for entering light into the light guiding area, A reflective surface that extends from the end of the light entry surface and reflects the light in the light guide region, an LED module in which a plurality of LEDs are alternately and discretely arranged along the light incident surface, and the predetermined LED And a color unevenness correcting resistor connected in parallel to each other.

  ADVANTAGE OF THE INVENTION According to this invention, the surface illumination apparatus which can obtain favorable display quality using a discrete light source row | line | column, and a liquid crystal display device provided with the same are realizable.

It is a disassembled perspective view which shows schematic structure of the liquid crystal display device provided with the backlight unit as a surface illumination apparatus by one embodiment of this invention. It is a figure which shows the main structures of the backlight unit 6 which cut | disconnected the liquid crystal display device shown in FIG. 1 of one Embodiment of this invention by the AA line. It is a figure which shows the arrangement | positioning relationship of the light emission surface 16 of the light-guide plate 11 of the backlight unit 6 and LED module 15 by one Embodiment of this invention in the state seen in the normal line direction of the light emission surface 16. FIG. It is a figure which shows schematic structure of the LED module by Example 1 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 2 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 3 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 4 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 5 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 6 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 7 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 8 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 9 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 10 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 11 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 12 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 13 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 14 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 15 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 16 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 17 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 18 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 19 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 20 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 21 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 22 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 23 in one embodiment of this invention. It is a figure which shows schematic structure of the LED module by Example 24 in one embodiment of this invention. It is a figure which shows the arrangement | positioning relationship of the light emission surface 16 of the light-guide plate 11 of the backlight unit and LED module 15 by Example 25 in one embodiment of this invention in the state seen in the normal line direction of the light emission surface 16. FIG. . It is a perspective view which shows schematic structure of the LED module 15 by Example 26 in one embodiment of this invention. It is a figure which shows typically the light-guide plate and LED module which are used with the proposed backlight unit.

A surface illumination device using a discrete light source array and a liquid crystal display device including the same according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing a schematic structure of a liquid crystal display device provided with a backlight unit as a surface illumination device according to the present embodiment. FIG. 2 shows a main structure of the backlight unit 6 obtained by cutting the liquid crystal display device shown in FIG. 1 along the line AA. As shown in FIGS. 1 and 2, the liquid crystal display device 1 according to the present embodiment includes a liquid crystal display panel 2 (not shown in FIG. 2) in which liquid crystal is sealed between a pair of substrates, and a backlight that is a surface illumination device. And a unit 6.

  The backlight unit 6 includes a light guide plate 11 formed of, for example, a rectangular thin plate-like transparent member having a predetermined plate thickness. The light guide plate 11 has a light emission region (hereinafter referred to as a light emission surface) 16 that emits light in a planar distribution on the side facing the liquid crystal display panel 2. The surface facing the light exit surface 16 of the light guide plate 11 is a light scattering surface on which scattering dots 24 functioning as a light extraction portion are printed. A reflection sheet 22 is disposed on the light scattering surface side of the light guide plate 11 facing the light exit surface 16.

  A region sandwiched between the light exit surface 16 of the light guide plate 11 and the light scattering surface opposite to the light exit surface 16 is a light guide region for guiding light to the light exit surface 16. Of the four side surfaces surrounding the light emitting surface 16 and the outer periphery of the light scattering surface, the opposing side surfaces on the long side, for example, are light incident surfaces 12 that allow light to enter the light guide region. Two side surfaces extending by connecting both ends of the two opposing light incident surfaces 12 are reflection surfaces 13 that reflect light in the light guide region.

  An LED module 15 including a discrete light source array is disposed on the light incident surface 12 of the light guide plate 11. The LED module 15 includes, for example, a plurality of types of LEDs 7 that emit light having different emission wavelength spectra and are discretely arranged along the light incident surface 12. Around the LED module 15, a reflector (reflecting plate) 20 for efficiently allowing light from the LED module 15 to enter the light guide plate 11 is disposed.

  Between the light guide plate 11 and the liquid crystal display panel 2, a gas space portion 30 having a predetermined thickness for efficiently mixing the light from the LED module 15 is provided. Between the gas space 30 and the liquid crystal display panel 2, optical sheets such as a transmissive diffusion plate 3 and lens sheets 4, 5 having a thickness of about 2 mm are disposed.

  Thus, the backlight unit 6 has a configuration in which the reflection sheet 22, the light guide plate 11, the gas space 30, and the optical sheets 3, 4, and 5 are stacked in this order. These components are fixed by the housing 60.

  Next, light mixing and light emission operations in the backlight unit 6 will be briefly described. As shown in FIG. 2, the light emitted from the LED module 15 and incident from the light incident surface 12 of the light guide plate 11 is guided through the light guide region and scattered by the scattering dots 24, and part of the light is emitted. The light is emitted from the surface 16 to the gas space 30, and the remainder is reflected by the reflection sheet 22, returned to the light guide region of the light guide plate 11 again, and reflected again by the scattering dots 24 and finally from the light emission surface 16 to the gas space 30. To ejaculate. These emitted lights are emitted as light that is close to the in-plane direction of the light emitting surface 16 and travels in a direction having a large angle θ from the normal direction of the light emitting surface 16. For this reason, the light emitted from the light exit surface 16 does not enter the liquid crystal display panel 2 immediately, and proceeds in the gas space 30 for a while. As a result, the light extracted in the vicinity of the light incident surface 16 and not mixed with the light from the other LEDs 7 is mixed with the other light while traveling through the gas space 30 and spreads over a wide area of the panel 2. Therefore, uneven color and uneven brightness are not visible. That is, the gas space portion 30 has a function of mixing and equalizing light having different emission wavelength spectra or light of different light amounts in the in-plane direction of the backlight unit 6. The optical sheets 3, 4, and 5 have the function of making the illumination light color and the illumination light amount uniform in the plane by mixing the light traveling at different angles and reorienting the angle at the same point in the plane. Have.

The light actually emitted from the light guide plate 11 is emitted in an oblique direction (θ = 70 to 80 °) with respect to the normal direction of the light emission surface 16. Therefore, if the light emitted from the light guide plate 11 at a certain emission point enters the transmissive diffusion plate 5 at a position advanced in the in-plane direction of the light guide plate by, for example, 50 mm from the emission point, the thickness of the gas space portion 30 is increased. The length (distance between the light exit surface 16 and the transmissive diffusion plate 5) needs to be 9 to 18 mm. In the present embodiment, the thickness of the gas space 30 is about 15 mm. Since the light diffuses while traveling through the gas space 30 by 50 mm, the light quantity of the light close to the vertical direction in addition to being mixed with other light is drastically reduced.

  FIG. 3 shows the positional relationship between the light emitting surface 16 of the light guide plate 11 and the LED module 15 of the backlight unit 6 according to the present embodiment as viewed in the normal direction of the light emitting surface 16. In FIG. 3, the opposite side surfaces on the long side of the rectangular light exit surface 16 are the light incident surfaces 12T and 12B, and the opposite side surfaces on the short side are the reflecting surfaces 13R and 13L.

  G (green) light-emitting LED 7G, R (red) light-emitting LED 7R, and B (blue) light-emitting LED 7B along the light incident surfaces 12T and 12B from the vicinity of the left end of the light incident surfaces 12T and 12B of the light guide plate 11. A plurality of LED sets (hereinafter referred to as “GRB” sets as necessary) 10 are arranged in a line.

  The reflection surfaces 13L and 13R extending from both ends of the two light incident surfaces 12T and 12B are finished to be mirror surfaces in order to efficiently perform regular reflection of light from the LED module 15. Note that a reflection sheet may be provided on the back side of the reflection surfaces 13L and 13R (outside of the reflection surfaces 13L and 13R) so that the light passing through the reflection surfaces 13L and 13R is returned to the light guide region. However, the present invention is not limited to these configurations, and the reflecting surfaces 13L and 13R may be formed by depositing or sticking a reflecting film on the polished surface, or a rough cutting surface state in which the reflecting surfaces 13L and 13R are not mirror-polished. However, this embodiment can be applied.

  Now, in the arrangement relationship between the LED module 15 having such a configuration and the light incident surfaces 12T and 12B, light from the LED 7G, LED 7R, and LED 7B near the arbitrary point is mixed at an arbitrary point inside the light emitting surface 16. Can produce light of a desired color.

  On the other hand, not only the direct light from the “GRB” set 10 at the left end of the light incident surface 12T but also the light of the “GRB” set 10 is reflected on the reflecting surface 13L at an arbitrary point near the upper left end of the light incident surface 12T. Light from the mirrored “BRG” set 10 ′ also arrives. Accordingly, “GRB” light reaches the vicinity of the arbitrary point from the right side of the reflecting surface 13L, and “GRB” light also reaches from the left side of the reflecting surface 13L. That is, in the vicinity of an arbitrary point in the vicinity of the upper part of the reflecting surface 13L, this is equivalent to one set of six “BRGGRB” LEDs being arranged in order from the left side of the figure, and among them, 4 closer to the arbitrary point. The light from “RGGR” of the LED sets will be mixed relatively strongly and “B” will not be present at all.

  Therefore, in order to relatively eliminate the shortage of the blue component at the arbitrary point, control is performed so that the light amount of the LED 7R of the “GRB” set 10 at the left end of the light incident surface 12T is smaller than the other LEDs 7R. In an LED drive circuit (not shown) in the LED module 15, for example, by flowing a current that is smaller by a predetermined amount than the current that flows in the LED 7 </ b> R in the other LED set 10 to the LED 7 </ b> R of the “GRB” set 10 at the left end of the light incident surface 12 </ b> T. The light having a light amount smaller than the other LEDs 7R by a predetermined amount can be emitted from the LED 7R on the left end side of the light incident surface 12T.

  Thereby, it is possible to obtain a balanced white light by suppressing the intensity of red to prevent color unevenness, and to significantly reduce the color unevenness in the vicinity of the upper end portion of the reflecting surface 13L. With the same configuration, the color unevenness near the lower end of the reflecting surface 13L and the upper and lower ends of the reflecting surface 13R can be significantly reduced.

Hereinafter, a specific configuration of the LED module 15 that can reduce color unevenness will be described using various embodiments.
Example 1
FIG. 4 shows a schematic configuration of the LED module 15 according to Example 1 of the present embodiment. FIG. 4A exemplarily shows the left end of the light incident surface 12T and the “GRB” set 10 adjacent thereto. In the LED module 15, the G (green) light emitting LEDs 7G are connected in series. Similarly, R (red) light emitting LEDs 7R and B (blue) light emitting LEDs 7B are also connected in series. Illustration of an LED driver that supplies current to LEDs of each color connected in series is omitted.

  Here, a color unevenness correction resistor (color unevenness correction resistor) 40 is connected in parallel to the LED 7R in the “GRB” set 10 at the left end of the light incident surface 12T. The color unevenness correcting resistor 40 functions as a current bypass resistor for the LED 7R on the left end side of the light incident surface 12T. When the resistance value of the color unevenness correction resistor 40 is set to 10Ω (ohms) or less, almost no current flows through the LED 7R on the left end side of the light incident surface 12T. Therefore, the resistance value of the color unevenness correction resistor 40 is about 10Ω to 30Ω. Is preferred.

  As described above, according to the present embodiment, the color unevenness correction resistor is connected in parallel to the LED that causes color unevenness and brightness unevenness. As a result, the current that originally flowed through the LED is bypassed, and the amount of current flowing through the LED can be suppressed and the amount of light of the LED can be reduced. Therefore, uneven color and uneven brightness can be adjusted.

  FIG. 4B shows a modification of FIG. The configuration shown in FIG. 4A is not suitable for correcting fine color unevenness because the resistance value of the color unevenness correcting resistor 40 is low. In addition, it is difficult to perform correction of LED performance variations. Therefore, as shown in FIG. 4B, the second color unevenness correction resistor 42 is connected in series to the LED that causes color unevenness and brightness unevenness (in this example, the LED 7R on the left end side of the light incident surface 12T). The value of the current flowing through the LED is accurately controlled by resistance division with the uneven color correction resistor 40. According to this configuration, color unevenness can be corrected with higher accuracy than the configuration shown in FIG.

(Example 2)
FIG. 5 shows a schematic configuration of the LED module 15 according to Example 2 of the present embodiment. FIG. 5A exemplarily shows the left end of the light incident surface 12T and the “GRB” set 10 adjacent thereto. In the following embodiments, the same reference numerals are given to configurations having the same operational effects as those described before, and the description thereof is omitted. The configuration shown in FIG. 5A is characterized in that an uneven color correction resistor 41 made up of a variable resistor is used in place of the uneven color correction resistor 40 of the first embodiment. Although it is difficult to correct the unevenness of the color even when the fixed resistance as in the first embodiment includes the LED performance variation, it is possible to realize correction individually corresponding to each LED by replacing with a variable resistor.

  FIG. 5B shows a modification of FIG. The second color unevenness correction resistor 42 is connected in series to the LED that causes color unevenness and brightness unevenness, and the current value flowing through the LED is accurately controlled by resistance division with the color unevenness correcting resistor 41. is there.

(Example 3)
FIG. 6 shows a schematic configuration of the LED module 15 according to Example 3 of the present embodiment. FIG. 6A exemplarily shows the left end of the light incident surface 12T (the end portion on the reflective surface 13L side) and the adjacent “GRB” set 10. The configuration of this embodiment is characterized in that a switch 43 is provided on the side of the current unevenness color unevenness correction resistors 40 and 41 (41 is illustrated in the figure). When it is not necessary to control the light quantity of the LED, the current bypass function can be cut off by turning off the switch 43.

  FIG. 6B shows a modification of FIG. Color unevenness and luminance unevenness mainly occur at the four corners of the light exit surface 16. For this reason, in consideration of the cost, it is only necessary to correct the color unevenness at the four corners of the light exit surface 16. Therefore, when cost reduction is desired, the color unevenness correction resistors 40 and 41 may be provided for one of the three LEDs at the end of the LED module 15. For example, if it is desired to adjust the chromaticity x value of the xy chromaticity coordinates at the end of the light incident surface 12T on the reflecting surface 13L side, it is desired to provide a color unevenness correction resistor for the red LED 7R and adjust the chromaticity y value. A color unevenness correction resistor may be provided in the green LED 7G. Therefore, in this modification, when adjusting the chromaticity y value, the color unevenness correction resistor 41 is connected in parallel with respect to the LED that causes color unevenness or brightness unevenness (for example, the LED 7G on the left end side of the light incident surface 12T). An example in which the second color unevenness correction resistor 42 is connected in series and a switch 43 is provided on the color unevenness correction resistor 41 side is shown.

Example 4
FIG. 7 shows a schematic configuration of the LED module 15 according to Example 4 of the present embodiment. FIG. 7A is similar to the combination of the configurations of FIGS. 6A and 6B of Example 3, and the LED module 15 has three LEDs at the end on the reflecting surface 13 side. A configuration in which the uneven color correction resistor 41 is provided in each of the middle two LEDs 7G and 7R is shown. In this way, if the chromaticity x value is to be adjusted, the resistance value of the color unevenness correcting resistor 41 of the red LED 7R is adjusted, and if the chromaticity y value is to be adjusted, the color unevenness correction of the green LED 7G is performed. The resistance value of the resistor 41 may be adjusted. If color unevenness correction is unnecessary, each switch 43 may be turned off.

  FIG. 7B shows a modified example of FIG. 7A, in which two LEDs 7G and 7B out of three LEDs at the end of the reflecting surface 13 side of the LED module 15 are used to correct color unevenness. A configuration in which resistors 40 and 41 are provided is shown. In this case as well, color unevenness correction similar to the configuration of FIG.

(Example 5)
FIG. 8 shows a schematic configuration of the LED module 15 according to Example 5 of the present embodiment. FIG. 8 shows the color unevenness correction resistor 41 for each of the three LEDs 7G, 7R, 7B out of the three LEDs at the reflection surface 13L and 13R side ends of the LED module 15 respectively. The configuration is illustrated. Since the color uniformity cannot be recognized by the human eye unless the balance of the three primary colors is finely corrected, a color unevenness correction resistor 41 is provided for each of the three LEDs 7 at both ends of the LED module 15. In this way, highly accurate color unevenness correction can be performed. Current is supplied from the LED driver 59 to the LEDs 7 of each color connected in series.

(Example 6)
FIG. 9 shows a schematic configuration of the LED module 15 according to Example 6 of the present embodiment. FIG. 9 is characterized in that, in the configuration of the fifth embodiment, a switch 43 is provided on the color unevenness correction resistor 41 side for current bypass. When it is not necessary to control the light quantity of the LED, the current bypass function can be cut off by turning off the switch 43. As a result, when the uneven color correction is unnecessary, it is possible to prevent the uneven brightness due to the darkness of the LED due to the current bypass function.

(Example 7)
FIG. 10 shows a schematic configuration of the LED module 15 according to Example 7 of the present embodiment. FIG. 10 shows a configuration including an LED set 10 having a minimum unit arrangement of four sets of “GRBG” using, for example, two “G” at the reflection surface 13L and 13R side end portions of the LED module 15. It is an example to which the embodiment is applied.

When the three primary color LEDs 7R, 7G, and 7B are used, it is preferable to arrange the red or green LEDs 7R and 7G at both ends because the color unevenness can be easily corrected by arranging yellow components at both ends of the LED module 15. However, since the red and green LEDs 7R and 7G have large individual variations in luminance, the correction variation increases only with the color unevenness correction resistor. Further, since the LED 7 has a large deterioration variation, color unevenness due to the influence of the high-intensity LEDs 7R and 7G of red and green occurs with time. For this reason, an LED 7 (LED 7G in the figure) having the same color as both ends is arranged at the fourth from both ends of the LED module 15, and color unevenness correction is performed by the two LEDs 7, thereby reducing luminance variation due to LED deterioration. Further, the same effect can be obtained by making the second and fifth LEDs 7 from the both ends of the LED module 15 the same color.

(Example 8)
FIG. 11 shows a schematic configuration of the LED module 15 according to Example 8 of the present embodiment. FIG. 11 is characterized in that, in the configuration of the seventh embodiment, a switch 43 is provided on the color unevenness correction resistor 41 side for current bypass.

Example 9
FIG. 12 shows a schematic configuration of the LED module 15 according to Example 9 of the present embodiment. FIG. 12 is characterized in that the arrangement of the four end portions on the reflective surface 13 side of the LED module 15 is “red-green-blue-red” from the end. As shown in FIG. 11 of the eighth embodiment, the inventors have an arrangement in which “green-red-blue-green” or “green-blue-red-green” LED arrangement from the end is the smallest in color unevenness. Next, it was found that even the “red-green-blue-red” LED array can reduce the color unevenness. Conversely, it has also been found that the color unevenness increases when both ends are blue.

(Example 10)
FIG. 13 shows a schematic configuration of the LED module 15 according to Example 10 of the present embodiment. FIG. 13 is characterized in that the switch 43 of the eighth embodiment is replaced with a transistor 43a. Since electrical control is easier to correct, the manufacturing efficiency and adjustment accuracy can be improved by replacing the color unevenness correcting resistor with an electronic resistor.

(Example 11)
FIG. 14 shows a schematic configuration of the LED module 15 according to Example 11 of the present embodiment. FIG. 14 shows a configuration in which at least one LED (LED 7R in the drawing) at the end on the reflecting surface 13 side is individually driven among the three LEDs 7G, 7R, 7B at both ends of the LED module 15. In the LEDs 7G and 7B, LEDs of the same color are connected and driven in series, but for the LED 7R, the LEDs 7R at the end of the reflecting surface 13 are individually driven. 40 or more LEDs 7 are usually mounted on the LED module 15, and the three-color LEDs 7G, 7R, and 7B are driven by 3 to 4 systems (green 2 systems) of wiring. In this embodiment, at least one LED 7 out of three at both ends is individually driven by current, thereby controlling the current value and correcting the color unevenness.

(Example 12)
FIG. 15 shows a schematic configuration of the LED module 15 according to Example 12 of the present embodiment. FIG. 15 has the same configuration as that of the eleventh embodiment, and the color unevenness is corrected by individually controlling the current at the four systems at both ends of the LED module 15. Further, in the same manner as in the seventh embodiment, in consideration of deterioration variation of the LED 7, the fourth LED 7 (LED 7G in the figure) having the same color as both ends is arranged from the end, and the end portion and the second two LEDs for green are arranged. Each of the LEDs 7G corrects color unevenness. Further, the same effect can be obtained by making the second and fifth LEDs 7 from the both ends of the LED module 15 the same color.

(Example 13)
FIG. 16 shows a schematic configuration of the LED module 15 according to Example 13 of the present embodiment. FIG. 16 is the same as that of the twelfth embodiment, but has a configuration in which the end portion and the fourth two LEDs 7G for green are connected in series to reduce the number of individual drives.

(Example 14)
FIG. 17 shows a schematic configuration of the LED module 15 according to Example 14 of the present embodiment. FIG. 17 is characterized in that four white LEDs 7W are arranged at both ends of the LED module 15. FIG. The LED 7 that controls the distribution of the four corners where color unevenness is likely to occur is white, and a high-quality LED backlight unit 2 can be realized at low cost. Four white LEDs 7W at both ends are connected in series at each end so as to keep the luminance uniform by current control.

(Example 15)
FIG. 18 shows a schematic configuration of the LED module 15 according to Example 15 of the present embodiment. The configuration shown in FIG. 18 is a modification of the configuration of the fourteenth embodiment, and color unevenness (in this case, luminance unevenness) is observed in each of the four end LEDs 7W at the reflection surface 13L and 13R side ends of the LED module 15. A configuration in which correction resistors 41 are provided is illustrated.

(Example 16)
FIG. 19 shows a schematic configuration of the LED module 15 according to Example 16 of the present embodiment. In this configuration, the white LED 7W is individually controlled by the LED driver 59 to correct the luminance.

(Example 17)
FIG. 20 shows a schematic configuration of the LED module 15 according to Example 17 of the present embodiment. As described in the seventh embodiment, it is desirable that both ends of the LED module 15 are yellow components. Therefore, in this embodiment, the yellow LED 7Y, the cyan LED 7C, and the magenta LED 7M are arranged in this order from both ends of the LED module 15, and the red, green, and blue LEDs 7R, 7G, and 7B extend along the light incident surface 12 from the fourth end onward. Alternately arranged discretely.

(Example 18)
FIG. 21 shows a schematic configuration of the LED module 15 according to Example 18 of the present embodiment. In this embodiment, two color LEDs 7 of three colors of yellow, cyan, and magenta are arranged at the end portion on the reflecting surface 13 side, and the LED 7 of one color of red or blue is arranged on the third from the end portion on the reflecting surface 13 side. Are arranged, and red, green, and blue LEDs are alternately and discretely arranged along the light incident surface 12 from the fourth end on the reflection surface 13 side end. For example, in the configuration shown in FIG. 21, two colors (yellow and cyan) are selected from yellow, cyan, and magenta, and one color (red or blue) is selected from the three primary colors. Yellow is an intermediate color between red and green, cyan is an intermediate color between green and blue, and when yellow and cyan are arranged at both ends, the red or blue component is insufficient, so the third color selects the red or blue of the insufficient color . The third color depends on the component intensity of the LED.

(Example 19)
FIG. 22 shows a schematic configuration of the LED module 15 according to Example 19 of the present embodiment. The configuration shown in FIG. 22 is a modification of the configuration of the seventeenth embodiment, and is a color unevenness correction resistor at each of the three end portions of the LEDs 7Y, 7C, and 7M at the reflection surface 13L and 13R side ends of the LED module 15. A configuration in which 41 and a switch 43 are provided is illustrated.

(Example 20)
FIG. 23 shows a schematic configuration of the LED module 15 according to Example 20 of the present embodiment. The LED driver 59 selects two colors of LEDs 7 (yellow LED 7Y and cyan LED 7C in the figure) from yellow, cyan, and magenta.
The EDs 7R, 7G, and 7B are configured to be controlled for each same color.

(Example 21)
FIG. 24 shows a schematic configuration of the LED module 15 according to Example 21 of the present embodiment. In the LED configuration shown in FIG. 20 according to the seventeenth embodiment, the LED driver 59 corrects the luminance and chromaticity by individually controlling the currents of the three colors of LEDs 7Y, 7C, and 7M of yellow, cyan, and magenta.

(Example 22)
FIG. 25 shows a schematic configuration of the LED module 15 according to Example 22 of the present embodiment. In the LED configuration shown in FIG. 21 according to the eighteenth embodiment, the luminance and chromaticity are corrected by individually controlling the current of the yellow LED 7Y, cyan LED 7C, red or blue LED 7R or 7B by the LED driver 59.

(Example 23)
FIG. 26 shows a schematic configuration of an LED module according to Example 23 of the present embodiment. FIG. 26A shows the arrangement relationship between the light emitting surface 16 of the light guide plate 11 and the LED module 15 of the backlight unit according to the present embodiment as viewed in the normal direction of the light emitting surface 16. In FIG. 26A, the opposite side surfaces on the short side of the rectangular light exit surface 16 are the light incident surfaces 12T and 12B, and the opposite side surfaces on the long side are the reflecting surfaces 13R and 13L. FIG. 26B shows a schematic configuration of the LED modules 15, 15R, 15L according to the present embodiment. The LEDs 8 of the LED modules 15R and 15L are individually driven by the LED driver 59.

G (green) light-emitting LED 7G, R (red) light-emitting LED 7R, and B (blue) light-emitting LED 7B along the light incident surfaces 12T and 12B from near the upper end portions of the light incident surfaces 12T and 12B of the light guide plate 11. Are arranged in a line at a substantially equal interval in this order.
On the other hand, G (green) light emitting LED 7G, B (blue) light emitting LED 7B, and R (red) from the vicinity of the lower end of light incident surfaces 12T, 12B of light guide plate 11 along light incident surfaces 12T, 12B. A plurality of LEDs 7 in which the color light emitting LEDs 7R are arranged in this order at substantially equal intervals are arranged side by side.

  On the reflective surface 13R side, LED modules 15R in which B (blue) light emitting LEDs 8B are disposed at both ends of the reflective surface 13R are disposed. On the reflective surface 13L side, LED modules 15L in which R (red) light emitting LEDs 8R are disposed at both ends of the reflective surface 13L are disposed. The LEDs 8R and 8B function as color unevenness correction LEDs disposed at the four corners of the light exit surface 16.

  As already described with reference to FIG. 3, even in the configuration of the LED module 15 in FIG. 26A, red is insufficient at the lower two corners of the light emitting surface 16 due to the mirror effect of the reflecting surface 13 </ b> L. On the other hand, due to the mirror effect of the reflecting surface 13R, blue is insufficient at the upper two corners of the light exit surface 16. By arranging the insufficiently colored LEDs as color unevenness correction LEDs, the color unevenness can be corrected. Up to Example 22, the idea was to reduce the current flowing through the LED and reduce the component luminance, but Example 23 is an ideal correction method that can compensate for the peripheral light quantity ratio in order to compensate for the insufficient color.

(Example 24)
FIG. 27 shows a schematic configuration of an LED module according to Example 24 of the present embodiment. FIG. 27 shows a configuration in which correction resistors 41a are connected in parallel to the color unevenness correction LEDs 8R and 8B shown in FIG.

(Example 25)
FIG. 28 shows the positional relationship between the light emission surface 16 of the light guide plate 11 of the backlight unit 11 and the LED module 15 according to Example 25, as viewed in the normal direction of the light emission surface 16. In the configuration shown in FIG. 28, in addition to the configuration shown in FIG. 26 (a), a color sensor 50 is arranged at each of the four corners of the light emission surface 16 for control in the embodiments 23 and 24. This is a control method. The color sensor 50 is arranged on the back surface of the light emission surface 16 at the four corners where the color unevenness occurs (the back surface of the light guide plate), and the luminance and chromaticity information is sent to the microcomputer to set the target chromaticity and luminance to the current value or electronic resistance. Control the value to correct it. The priority is chromaticity correction. Alternatively, the target chromaticity luminance may be based on the output of the color sensor at the center.

(Example 26)
FIG. 29 is a perspective view showing a schematic configuration of the LED module 15 according to Example 26 of the present embodiment. When the mechanical type is selected as the color unevenness (brightness unevenness) correction resistor 41 composed of a variable resistor, the color unevenness (brightness unevenness) correction resistor 41 is mounted on the end of the LED module 15 and mounted on the mold housing or the sheet metal housing. An adjustment hole is provided, and the chromaticity is corrected by adjusting the current value of the LED 7 at both ends of the LED module 15 by increasing or decreasing the resistance value during manufacture.

  As described above, according to the present embodiment, the edge type LED with a small number of LEDs can be obtained by controlling the light quantity of the LED that causes color unevenness or brightness unevenness or adding an auxiliary LED. Color unevenness at the four corners of the display area that occurs in the backlight method can be reduced.

The present invention is not limited to the above embodiment, and various modifications can be made.
In the said embodiment, although the LED module 15 was arrange | positioned at the both sides of the light-guide plate 11, you may arrange | position the LED module 15 not only to this but only to one side. Further, when the cross section is a wedge-shaped light guide plate, the LED module 15 may be disposed only on one side.

  In the above embodiment, the invention is applied to one light guide plate of a parallel plate type. However, the present invention is not limited to this, and a light guide plate having a structure in which two light guide plates are superposed is used for a side light type. The present invention can be applied to a backlight unit having any other structure including a planar two-stage type. Furthermore, the present invention can be applied not only to the backlight unit but also to the front light unit.

  Moreover, in the said embodiment, although the light-guide plate 11 formed with the transparent member is used for a light guide area | region, this invention is not limited to this. For example, as long as a reflecting member is attached to the side surface of the light guide region, the light guide region may be a hollow air layer.

  In the above embodiment, an LED is used as a light source, but the present invention is not limited to this, and any light emitter can be used as long as it can constitute a discrete light source array. Further, in the surface illumination device described in the above embodiment, the color arrangement of the LEDs may be mirror-symmetric with the same color in order from both ends.

The surface illumination device according to the present embodiment described above and the liquid crystal display device including the surface illumination device are summarized as follows.
(Appendix 1)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
An LED module in which a plurality of LEDs are alternately and discretely arranged along the light incident surface;
And a color unevenness correcting resistor connected in parallel to the predetermined LED.
(Appendix 2)
In the surface illumination device according to attachment 1,
The color unevenness correction resistor is a variable resistor.
(Appendix 3)
In the surface illumination device according to appendix 1 or 2,
A surface illumination device, wherein a switch is provided in series with the color unevenness correction resistor.
(Appendix 4)
In the surface illumination device according to any one of appendices 1 to 3,
A surface illumination device comprising: a second color unevenness correction resistor connected in series to the predetermined LED.
(Appendix 5)
In the surface illumination device according to any one of appendices 1 to 4,
The said predetermined LED is at least 1 of the three arrange | positioned at the said reflection surface side edge part of the said LED module.
(Appendix 6)
In the surface illumination device according to any one of appendices 1 to 4,
The said predetermined LED is two of the three arrange | positioned at the said reflective surface side edge part of the said LED module. The surface illumination apparatus characterized by the above-mentioned.
(Appendix 7)
In the surface illumination device according to any one of appendices 1 to 4,
The predetermined LED is three or a multiple of three arranged at the reflection surface side end of the LED module.
(Appendix 8)
In the surface illumination device according to any one of appendices 1 to 7,
The LED has different spectral characteristics.
(Appendix 9)
In the surface illumination device according to any one of appendices 1 to 4,
The predetermined LED is four or multiples of four having three types of spectral characteristics, which are arranged at the reflection surface side end of the LED module.
(Appendix 10)
In the surface illumination device according to any one of appendices 1 to 4,
The surface illumination device according to claim 1, wherein the predetermined LED is four or a multiple of four having four types of spectral characteristics arranged at an end of the LED module on the reflection surface side.
(Appendix 11)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
A surface illumination device comprising: a plurality of LEDs arranged alternately and discretely along the light incident surface, and an LED module that individually drives at least one of the LEDs on the reflection surface side end portion.
(Appendix 12)
In the surface illumination device according to any one of appendices 1 to 11,
In the LED, the array of four end portions on the reflection surface side of the LED module is in the order of green-red-blue-green from the end.
(Appendix 13)
In the surface illumination device according to any one of appendices 1 to 11,
In the LED, the array of four end portions on the reflection surface side of the LED module is in the order of green-blue-red-green from the end.
(Appendix 14)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
An area illuminating device comprising: an LED module in which at least one white LED is arranged at an end portion on the reflection surface side, and a plurality of LEDs are arranged alternately and discretely along the light incident surface.
(Appendix 15)
In the surface illumination device according to attachment 14,
A luminance unevenness correcting resistor connected in parallel to the white LED;
And a switch for switching the luminance unevenness correcting resistor.
(Appendix 16)
In the surface illumination device according to attachment 14,
The surface illumination device, wherein the white LEDs are individually driven.
(Appendix 17)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
Three color LEDs of yellow, cyan, and magenta are arranged at the end on the reflection surface side, and red, green, and blue LEDs are alternately discretely distributed along the light incident surface after the fourth from the end. A surface illumination device comprising: an LED module disposed.
(Appendix 18)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
Two color LEDs of three colors of yellow, cyan, and magenta are arranged on the reflection surface side end, and a red or blue LED is arranged on the third from the end, and from the end A surface illumination device comprising a LED module in which red, green, and blue LEDs are alternately and discretely arranged along the light incident surface after the fourth.
(Appendix 19)
In the surface illumination device according to appendix 17 or 18,
An uneven color correction resistor connected in parallel to the LED at the end of the reflecting surface;
And a switch for switching the color unevenness correction resistor.
(Appendix 20)
In the surface illumination device according to appendix 17 or 18,
The surface illumination device, wherein the LEDs at the reflection surface side end portions are individually driven.
(Appendix 21)
A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
An LED module in which a plurality of LEDs are alternately and discretely arranged along the light incident surface;
A surface illumination device comprising: uneven color correction LEDs arranged at the four corners of the light emission region.
(Appendix 22)
In the surface illumination device according to attachment 21,
A surface illumination device comprising a correction resistor connected in parallel to the color unevenness correction LED.
(Appendix 23)
In the surface illumination device according to appendix 21 or 22,
The surface illumination device, wherein the color unevenness correction LEDs are individually driven.
(Appendix 24)
In the surface illumination device according to any one of appendices 1 to 23,
The surface illumination device characterized in that the color arrangement of the LEDs is the same color in order from both ends of the reflection surface.
(Appendix 25)
In the surface illumination device according to any one of appendices 1 to 24,
A surface illumination device, wherein photosensors for controlling luminance and chromaticity are arranged at the four corners and the back or front surface of the center of the light emission region.
(Appendix 26)
In the surface illumination device according to any one of appendices 1 to 25,
The surface illumination device, wherein the LED module is arranged on one side of the light incident surface.
(Appendix 27)
In the surface illumination device according to appendices 1 to 26,
A surface illumination device comprising a housing provided with an adjustment hole in a sheet metal or a mold so that the resistance for correcting the color unevenness (brightness unevenness) can be adjusted from the outside.
(Appendix 28)
In the surface illumination device according to any one of appendices 1 to 27,
A surface illuminating device characterized by reducing the unevenness of color when white by aligning the luminance ratio of the four corners of each color of LED primary color light and unifying the peripheral luminance ratio of each color.
(Appendix 29)
In a liquid crystal display device including a liquid crystal sealed between a pair of substrates disposed opposite to each other,
A liquid crystal display device comprising the surface illumination device according to any one of appendices 1 to 28.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display panel 3 Transmission type diffuser plate 4, 5 Lens sheet 6 Backlight unit 7, 8, 77 LED
10, 10 'LED set 11 Light guide plate 12 Light incident surface 13 Reflective surface 14 Reflective sheet 15, 15L, 15R LED module 16 Light exit surface 20 Reflector 22 Reflective sheet 24 Scattering dot 30 Gas space portion 40, 41 Color unevenness correction resistor 42 Second color unevenness correction resistor 43 Switch 43a Transistor 50 Color sensor 59 LED driver 60 Housing

Claims (4)

A light emitting area that emits light in a planar distribution; and
A light guiding region for guiding light to the light emitting region;
A light incident surface for entering light into the light guide region;
A reflective surface extending from the end of the light incident surface and reflecting light in the light guide region;
An LED module in which at least one white LED is disposed only at the reflection surface side end portion, and a plurality of LEDs having different spectral characteristics are disposed alternately and discretely along the light incident surface. Surface lighting device. The surface illumination device according to claim 1,
A luminance unevenness correcting resistor connected in parallel to the white LED;
And a switch for switching the luminance unevenness correcting resistor.   The surface illumination device according to claim 1,
  Driving the white LEDs individually
  A surface illumination device. In a liquid crystal display device including a liquid crystal sealed between a pair of substrates disposed opposite to each other,
The liquid crystal display device characterized by having a surface lighting device according to any one of claims 1 to 3.

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