JP2006310163A - Strut, backlight device using this strut, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain unevenness of brightness caused by a strut while surely holding an optical structure such as a dispersion plate. <P>SOLUTION: On a light source of the backlight device, a light transmitting material is used at least at a part contacting a top end part of the strut 30 for keeping a space between a dispersion plate 141 into which light from a light source, for example, that from a light emitting diode is incident, and the light emitting diode constant. With this, light L0 irradiated on the strut 30 is taken in, and the light L0 taken in is guided upward into the inside of the strut, and light Lr0 is irradiated from the part in contact with the dispersion plate 141 at the tip end part. A transmittance of the light-transmitting material constituting the strut 30, a combination, a structure, or the like of light-transmitting materials are changed to control light volumes of the irradiated light Lr0, and brightness of the surface of the dispersion plate 141 above the strut 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a column that holds, for example, a space between a diffuser plate and a light source on which light from a light source is incident, a backlight device and a liquid crystal display device using the column.

  In recent years, instead of CRT (Cathode Ray Tube) as a display device for a television receiver, it is very thin such as a liquid crystal display (LCD) or a plasma display (PDP). Display devices have been proposed and put into practical use. In particular, liquid crystal display devices using liquid crystal display panels can be driven with low power consumption, and the spread of the large liquid crystal display panels has been promoted, leading to technical research and development. It has been.

In such a liquid crystal display device, a backlight system in which a color image is displayed by illuminating a transmissive liquid crystal display panel including a color filter with a backlight device that illuminates the surface from the back side becomes the mainstream. ing.
As a light source of the backlight device, a cold cathode fluorescent tube (CCFL) that emits white light using a fluorescent tube and a light emitting diode (LED) are promising.

  In particular, with the development of blue light emitting diodes, light emitting diodes that emit the three primary colors of light, red light, green light, and blue light, have been prepared, and the red light, green light, and blue light emitted from these light emitting diodes have been prepared. By mixing light, white light with high color purity can be obtained. Therefore, by using this light emitting diode as the light source of the backlight device, the color purity through the liquid crystal display panel is increased, so that the color reproduction range can be greatly expanded compared with the CCFL. Furthermore, the brightness of the backlight device can be significantly improved by using a high-output light-emitting diode chip (LED chip).

Using such a light emitting diode, for example, a direct type, that is, a backlight device in which the light emitting diode is arranged directly under the light emitting surface of the device has been proposed (for example, see Non-Patent Document 1).
Nikkei Electronics (Nikkei BP), December 20, 2004 (No. 889) pp. 123-130

  Incidentally, as described in Non-Patent Document 1, a backlight device for a liquid crystal display device requires a structure that supports an optical structure such as a diffusion plate. For example, the diffusion plate is generally made of resin and has a thickness of about 2 mm, although it varies depending on the size of the liquid crystal display panel, and does not have a structure that is rigid enough to maintain the plane itself. Therefore, a structure that supports the diffusion plate is required. For this structure, a column such as a cylinder or a cone is often used.

  FIG. 9 is a schematic cross-sectional view showing a general direct type backlight device. As shown in FIG. 9, a backlight device for a liquid crystal display device includes a frame (housing) 502, a reflective structure 520, a diffuser plate 541, and a column that holds the distance between the reflective structure 520 and the diffuser plate 541 constant. 530, which is composed of light emitting diodes 521R, 521G, and 521B of three colors of red, green, and blue arranged as light sources. The periphery of the diffuser plate 541 is supported by a frame 502 of the backlight device, and is supported by at least one column 530 near the center. Although not shown, a liquid crystal display panel is disposed on the diffusion plate 541. The three colors of light are mixed in a space formed between the reflective structure 520 and the diffuser plate 541, are emitted from the diffuser plate 541 as white light with uniform luminance, and enter the liquid crystal display panel.

  FIG. 10 shows the light state at the end of the column. The light emitted from each of the light emitting diodes 521R, 521G, and 521B becomes light 550 having uniform luminance while being repeatedly reflected by the reflection structure of the peripheral portion. However, a certain percentage of the light 551 is reflected on the surface of the column 530 and changes its angle toward the diffusion plate 541. Further, in order to increase the strength of the support column as a measure against the vibration and impact of the support column, if the diameter of the support column is increased to, for example, φ5 mm, as shown in FIG. In contrast to the shadowed area 561, a brightened area 562 occurs, resulting in uneven brightness. As the diameter of the column 530 increases, the shadow area 561 increases and the area ratio to the bright area 562 also increases.

  As a countermeasure for making the shadow inconspicuous, for example, it is conceivable to reduce the shadow, that is, to reduce the diameter of the column, but the strength of the column is affected. In recent years, the size of liquid crystal display devices has been increasing, and the larger the liquid crystal display panel, the larger the diameter of the columns 530 and the need to increase the number of the columns. Therefore, a large number of large shadow areas 561 are generated. The effect of uneven brightness cannot be ignored.

  The present invention has been made in view of this point, and an object of the present invention is to suppress the occurrence of uneven brightness due to the support column while reliably holding an optical structure such as a diffusion plate.

  In order to solve the above-described problems, the present invention provides a support column supporting an optical structure that is provided in a backlight device or the like and receives direct light and indirect light from a light source. It is set as the structure by which the light transmissive material is used for some.

  According to the above configuration, the light irradiated to the portion made of the light-transmitting material of the support is taken into the support, and the captured light is guided upward through the light-transmitting material in the support. The light is emitted from the tip portion in contact with the structure. For example, it is possible to control the amount of light emitted from the tip of the column by considering the material used for the column, the combination of materials having different transmittances, the composition ratio, the combination shape, and the like.

  Further, the backlight device of the present invention is a backlight device having a support supporting an optical structure to which direct light and indirect light from a light source are incident, and at least a part of the support tip in contact with the optical structure is light. A support column made of a permeable material is used.

  According to the above configuration, it is possible to control the amount of light emitted from the front end portion of the column with respect to the optical structure such as a diffusion plate disposed above the column, and appropriately adjust the luminance of the surface of the optical structure. can do.

  Further, the backlight device of the present invention is a liquid crystal display device comprising: a transmissive liquid crystal display panel; and a backlight device that includes a plurality of light sources and illuminates the liquid crystal display panel from the back side. Has a support that supports an optical structure to which direct light and indirect light from a light source are incident, and the support is made of a light-transmitting material at least at a part of the support tip that contacts the optical structure. It is characterized by comprising.

  According to the above configuration, it is possible to control the amount of light directly above the support post emitted to the optical structure such as a diffusion plate disposed above the backlight device, and to appropriately adjust the brightness of the surface of the optical structure. can do. Therefore, the luminance unevenness and color unevenness of the liquid crystal display panel are reduced.

  As described above, according to the present invention, for example, an optical structure such as a diffusing plate of a backlight device can be securely held by a support, and the occurrence of uneven brightness due to the support can be suppressed. Therefore, the quality is improved by using the backlight device for a liquid crystal display device.

  Examples of the best mode for carrying out the present invention will be described below, but the present invention is not limited to the following examples.

  The present invention can be applied to, for example, a transmissive color liquid crystal display device 100 configured as shown in FIG. The transmissive color liquid crystal display device 100 includes a transmissive color liquid crystal display panel 110 and a backlight device 140 provided on the back side of the color liquid crystal display panel 110. Although not shown, the transmissive color liquid crystal display device 100 includes a receiving unit such as an analog tuner and a digital tuner that receives terrestrial and satellite waves, and a video signal that processes a video signal and an audio signal received by the receiving unit, respectively. An audio signal output unit such as a processing unit, an audio signal processing unit, a speaker that outputs an audio signal processed by the audio signal processing unit, and the like may be provided.

  In the transmissive color liquid crystal display panel 110, two transparent substrates (TFT substrate 111 and counter electrode substrate 112) made of glass or the like are arranged to face each other, and, for example, twisted nematic (TN) liquid crystal is provided in the gap. The liquid crystal layer 113 encapsulating the liquid crystal layer 113 is provided. On the TFT substrate 111, signal lines 114 arranged in a matrix, scanning lines 115, thin film transistors 116 serving as switching elements arranged at intersections of the signal lines 114 and the scanning lines 115, and pixel electrodes 117 are formed. Has been. The thin film transistor 116 is sequentially selected by the scanning line 115 and writes the video signal supplied from the signal line 114 to the corresponding pixel electrode 117. On the other hand, a counter electrode 118 and a color filter 119 are formed on the inner surface of the counter electrode substrate 112.

  The color filter 119 is divided into a plurality of segments corresponding to each pixel. For example, as shown in FIG. 2, it is divided into three segments of a red filter CFR, a green filter CFG, and a blue filter CFB which are three primary colors. The arrangement pattern of the color filter 119 includes a delta arrangement and a square arrangement, although not shown, in addition to the stripe arrangement shown in FIG.

The configuration of the transmissive color liquid crystal display device 100 will be described again with reference to FIG. In the transmissive color liquid crystal display device 100, the transmissive color liquid crystal display panel 110 having such a configuration is sandwiched between two polarizing plates 131 and 132, and white light is irradiated from the back side by the backlight device 140. By driving with an active matrix system, a desired full-color image can be displayed.
The backlight device 140 illuminates the color liquid crystal display panel 110 from the back side. As shown in FIG. 1, the backlight device 140 includes a diffusion plate 141 and a diffusion plate in a backlight case 120 in order to mix light emitted from the light source and light emitted from the light source into white light. An optical function sheet group 145 such as a diffusion sheet 142, a prism sheet 143, and a polarization conversion sheet 144 that are arranged on the plate 141 is provided.
The diffusing plate 141 makes the luminance emitted from the surface emission uniform by internally diffusing the light emitted from the backlight housing 120.

  In general, the optical function sheet group has, for example, a function of decomposing incident light into orthogonal polarization components, a function of compensating for a phase difference of light waves to achieve a wide-angle viewing angle and preventing coloring, a function of diffusing incident light, and a brightness improvement And is provided to convert the light emitted from the backlight device 140 into illumination light having optical characteristics optimal for illumination of the color liquid crystal display panel 110. . Therefore, the configuration of the optical function sheet group 145 is not limited to the diffusion sheet 142, the prism sheet 143, and the polarization conversion sheet 144 described above, and various optical function sheets can be used.

FIG. 3 shows a schematic configuration diagram in the backlight housing 120. As shown in FIG. 3, in this backlight device, a light emitting diode may be used as a light source, and although not shown, a CCFL or the like can also be used. In the illustrated example, the backlight housing 120 uses a red light emitting diode 21R that emits red light, a green light emitting diode 21G that emits green light, and a blue light emitting diode 21B that emits blue light as light sources. For example, the peak wavelengths of red light emitted from the red light emitting diode 21R, green light emitted from the green light emitting diode 21G, and blue light emitted from the blue light emitting diode 21B are about 640 nm, 530 nm, and 450 nm, respectively. The peak wavelengths of red light and blue light emitted by the red light emitting diode 21R and the blue light emitting diode 21B may be shifted from 640 nm to the long wavelength side and from 450 nm to the short wavelength side, respectively. In this way, when the peak wavelength is shifted to the long wavelength side and the short wavelength side, the color gamut can be expanded, so that the color reproduction range of the image displayed on the color liquid crystal display panel can be expanded.
In the following description, when the red light emitting diode 21R, the green light emitting diode 21G, and the blue light emitting diode 21B are collectively referred to, they are simply referred to as the light emitting diode 21.

  As the light-emitting diode 21, a lens-shaped light-emitting diode having a radiation directivity characteristic in the immediately upward direction may be used, or light is mainly emitted in the lateral direction, such as a light-emitting diode chip having other lens-shaped radiation directivity characteristics. A side emitting type having a lens function may be used.

As shown in FIG. 3, a plurality of the light emitting diodes 21 are arranged in a row in a desired order on the wiring board 22, thereby forming a light emitting diode unit 21n (n is a natural number). Each wiring board 22 is connected to a driving driver board (not shown).
In order to form the light emitting diode unit 21n, the order in which the light emitting diodes 21 are arranged on the wiring board 22 is a red light emitting diode 21R, a green light emitting diode 21G, and a blue light emitting diode 21B as shown in FIG. Although the most basic arrangement method or not shown, for example, the green light emitting diodes 21G are arranged at equal intervals, and the red light emitting diodes 21R and the blue light emitting diodes 21B are alternately arranged between the adjacent green light emitting diodes 21G. There are various arrangement methods such as order.
The arrangement of the light emitting diode units 21n in the backlight housing 120 may be arranged so that the longitudinal direction of the light emitting diode units 21n is in the horizontal direction, as shown in FIG. The light emitting diode units 21n may be arranged so that the longitudinal direction thereof is the vertical direction, or both may be combined.

The method of arranging the light emitting diode units 21n so that the longitudinal direction is the horizontal direction or the vertical direction is the same as the CCFL arrangement method used as the light source of the conventional backlight device. The designed design know-how can be used, and the cost and time required for manufacturing can be shortened.
The inner wall surface 120a of the backlight housing 120 is a reflecting surface or a diffusing surface that has been subjected to reflection processing in order to increase the utilization efficiency of the light emitted from the light emitting diode 21.

  FIG. 4 is a partial cross-sectional view taken along the line XX attached to the transmissive color liquid crystal display device 100 shown in FIG. 1 when the transmissive color liquid crystal display device 100 is assembled. As shown in FIG. 4, the color liquid crystal display panel 110 constituting the liquid crystal display device 100 includes spacers 103 a and 103 b formed by an external frame 101 that is an external housing of the transmissive color liquid crystal display device 100 and an internal frame 102. It is hold | maintained so that it may pinch. A guide member 104 is provided between the outer frame 101 and the inner frame 102, and the color liquid crystal display panel 110 sandwiched between the outer frame 101 and the inner frame 102 is displaced in the longitudinal direction. Is suppressed.

On the other hand, the backlight device 140 constituting the transmissive color liquid crystal display device 100 includes the diffusion plate 141 on which the optical function sheet group 145 is laminated as described above. Further, a reflection sheet 126 is disposed between the diffusion plate 141 and the backlight housing 120.
The reflection sheet 126 is disposed so that the reflection surface thereof faces the light incident surface 141 a of the diffusion plate 141 and is closer to the backlight housing 120 than the light emitting direction of the light emitting diode 21. As the reflection sheet 126, for example, a silver-enhanced reflection film formed by sequentially laminating a silver reflection film, a low refractive index film, and a high refractive index film on a sheet base material can be used. In addition, the reflection sheet 126 is mainly emitted from the light emitting diode 21 and radiated downward due to the radiation angle distribution thereof, or the inner wall surface 120a which is subjected to reflection processing of the backlight housing 120 and is used as a reflection surface. Reflects reflected light. The reflection sheet 126 may be subjected to a diffusion process.

The diffusion plate 141 is held by a bracket member 108 provided in the backlight housing 120 and is supported by the support column 30 according to the present invention near the center. In order to prevent a shadow from being generated on the surface of the diffusing plate 141 immediately above the support column 30, the support column 30 is configured by using a light transmitting resin for a part or all of the support column 30. The column having the configuration of the present invention will be described in detail later.
In addition, the fixing method of the support | pillar 30 forms a female screw (tap) in the bottom face of the support | pillar 30, for example, pinches | interposes the reflective sheet 126, and fixes it with a male screw (bolt). Alternatively, the bottom surface of the support column 30 may be bonded and fixed to the reflection sheet 126. Alternatively, as described in Non-Patent Document 1, the tip portion extending downward from the bottom surface of the support column may have an irreversible structure and may be fixed so as not to come out after being fitted into the hole provided in the reflection sheet 126.

  The transmissive color liquid crystal display device 100 having such a configuration is driven by a drive circuit 200 as shown in FIG. 5, for example. The driving circuit 200 includes a color liquid crystal display panel 110, a power source 210 that supplies driving power for the backlight device 140, an X driver circuit 220 and a Y driver circuit 230 that drive the color liquid crystal display panel 110, and video signals supplied from the outside. Or an RGB process processing unit 250 that receives a video signal received by a receiving unit (not shown) included in the transmissive color liquid crystal display device 100 and processed by the video signal processing unit, via an input terminal 240, and the RGB process. An image memory 260 and a control unit 270 connected to the processing unit 250, a backlight drive control unit 280 for driving and controlling the backlight device 140, and the like are provided.

In the drive circuit 200, the video signal input through the input terminal 240 is subjected to signal processing such as chroma processing by the RGB process processing unit 250, and is further suitable for driving the color liquid crystal display panel 110 from the composite signal. It is converted into an RGB separate signal and supplied to the control unit 270 and also supplied to the X driver 220 via the image memory 260.
Further, the control unit 270 controls the X driver circuit 220 and the Y driver circuit 230 at a predetermined timing according to the RGB separate signal, and supplies the X driver circuit 220 together with the video signal from the image memory 260. By driving the color liquid crystal display panel 110 with the RGB separate signal, an image corresponding to the RGB separate signal is displayed.

The backlight drive control unit 280 generates a pulse width modulation (PWM) signal from the voltage supplied from the power supply 210 and drives each light emitting diode 21 that is a light source of the backlight device 140. In general, the color temperature of a light emitting diode has a characteristic that it depends on an operating current. Therefore, in order to reproduce the color faithfully (with a constant color temperature) while obtaining a desired luminance, it is necessary to drive the light emitting diode 21 using a pulse width modulation signal to suppress the color change.
The user interface 300 selects a channel to be received by the above-described receiving unit (not shown), adjusts an audio output amount to be output by an audio output unit (not shown), or from the backlight device 140 that illuminates the color liquid crystal display panel 110. This is an interface for executing white light brightness adjustment, white balance adjustment, and the like.
For example, when the user adjusts the brightness from the user interface 300, the brightness control signal is transmitted to the backlight drive control unit 280 via the control unit 270 of the drive circuit 200. In response to the luminance control signal, the backlight drive control unit 280 changes the duty ratio of the pulse width modulation signal for each of the red light emitting diode 21R, the green light emitting diode 21G, and the blue light emitting diode 21B to change the red light emitting diode 21R, green The light emitting diode 21G and the blue light emitting diode 21B are driven and controlled.

Next, in the backlight device and the liquid crystal display device of the present invention, the schematic configuration of each example of the support will be described.
FIG. 6 shows a column according to an embodiment of the backlight device according to the present invention. In this example, in order to eliminate the shadow generated immediately above the support column, a light-transmitting resin, such as POM (polyoxymethylene; abbreviated polyacetal resin), is used for the support column material, and light is guided inside the support column. I did it. Although common in each of the following examples, the light-transmitting resin includes at least a part of a column tip that is in contact with an optical structure such as a diffusion plate, that is, an emission surface (a surface facing the optical structure). It is essential to be used for the part.
The support column 30 used in this example has a substantially conical shape, but is not limited to this example, and may have a cylindrical shape. In consideration of the luminance distribution above the support column, the shape in which the portion in contact with the diffusion plate 141 is narrow, that is, a cone, particularly a right cone is more preferable. The shape is not necessarily limited to a conical shape or a cylindrical shape, and may be a rectangular parallelepiped.

  As shown in FIG. 6, when the light L <b> 0 is irradiated on the conical surface of the support column 30 formed of a transmissive resin, the light L <b> 0 enters the support column 30. Part of the incident light L0 penetrates to the opposite side as transmitted light Lt0. Of the light incident on the inside of the column 30, the light reflected on the wall surface inside the column 30 without being transmitted to the outside is guided upward while being reflected several times on the wall surface inside the column 30. It is emitted as light Lr0.

  In this way, the light guided inside the column 30 is emitted from the column tip, so that no shadow caused by the column is generated on the diffusion plate. Note that by appropriately selecting the transmittance of the permeable resin forming the support, the amount of light emitted to the tip of the support can be controlled, and as a result, the luminance on the surface of the diffusion plate 141 can be adjusted.

FIG. 7 shows a column according to another embodiment of the backlight device according to the present invention. In this example, the struts are not formed as a single structure with a single permeable resin, but are formed from a combination of upper and lower parts made of materials having different transmittances. In this example, the transmissive portion 41 made of a resin having optical transparency is arranged on the upper side of the support column 40, that is, the portion including the contact portion with the diffusion plate 141, and the non-transmissive portion 42 is disposed on the lower side thereof. .
As shown in FIG. 7, as in the example of FIG. 6, the light L0 irradiated to the transmission part 41 transmits a part of the light Lt0 as it is and is emitted to the outside of the column 40, and a part of the light Lr0 is emitted from the column 40. The light is guided inside and emitted from the top. On the other hand, the light L <b> 1 irradiated to the non-transmissive portion 42 is reflected and is not guided into the support column 40.

  According to the configuration of this example, the amount of light emitted to the front end portion of the column can be controlled by the combination of the transmissive portion and the non-transmissive portion constituting the column. Further, the amount of light can be controlled by selecting each light-transmitting material or changing the composition ratio between the transmitting part and the non-transmitting part. Other effects are the same as in FIG.

FIG. 8 shows a column according to still another embodiment of the backlight device according to the present invention. In this example, the support is composed of a combination of the inside and the outside made of materials having different transmittances. In this example, the substantially cylindrical strong transmission part 51 made of a resin having a high light transmittance is arranged inside the support column 50 and the weak transmission part 52 having a low light transmission property is wrapped around the strong transmission part 51. Arranged outside. That is, a light-transmitting material is used for a part of the inside of the column that is continuous with a part of the column tip part that is an emission surface (a surface facing the optical structure), and continuously with a part of the column tip part. It is set as the structure which takes light in a part inside the pillar which is.
As shown in FIG. 8, a part of the light L <b> 2 irradiated to the weak transmission portion 52 located outside the support column 50 is first reflected and a part of the light L <b> 2 enters the support column 50. A part of the light incident in the support 50 is emitted as transmitted light Lt0 as it is, and the remaining light is repeatedly reflected at the boundary between the strong transmission part 51 and the weak transmission part 52 and guided to the tip part. And emitted as light Lr2 from the tip.

  According to the configuration of this example, the amount of light emitted to the front end portion of the column can be controlled by the combination of the strong transmission portion and the weak transmission portion constituting the column. Further, the amount of light can be controlled by selecting each light-transmitting material or changing the ratio of these components, such as changing the diameter of the inner strong transmitting portion. About other, there exists an effect similar to FIG.6 and FIG.7. In addition, the combination using the strong transmission part and weak transmission part of this example is also applicable to the support | pillar of the example of FIG.

  As described above, when the support of the above structure is applied to a backlight device such as a liquid crystal display device, the optical structure such as the diffusion plate is securely held by the support and the occurrence of uneven brightness due to this support is suppressed. Can do. Therefore, the image quality and quality of the liquid crystal display device are improved.

  In the example of the above-described embodiment, the direct type backlight device has been described as an example. However, the structure of the present invention is also applied to a side edge type backlight device or a backlight device of these types using a CCFL. Can be used.

  Further, as the transparent material used for the support, for example, colorless acrylic or the like can be used instead of the above-described POM (white), and the amount of light can be adjusted by a material having different light transmittance. Moreover, as long as it is a transparent material, it is not limited to resin, and glass or the like may be used.

  Further, the present invention is not limited to the above-described embodiments, and other materials, combinations of materials having different transmittances, composition ratios, combined shapes, and the like, as long as they do not depart from the spirit of the present invention. Of course, various modifications and changes are possible.

1 is a schematic exploded perspective view of an example of a liquid crystal display device shown as the best mode for carrying out the present invention. 1 is a schematic plan configuration diagram of an example of a color filter of a liquid crystal display panel according to a liquid crystal display device shown as the best mode for carrying out the present invention. 1 is a schematic perspective view of a backlight device according to a liquid crystal display device shown as the best mode for carrying out the present invention. 1 is a schematic cross-sectional configuration diagram of an example of a liquid crystal display device shown as the best mode for carrying out the present invention. 1 is a schematic block configuration diagram of an example of a drive circuit for driving a liquid crystal display device shown as the best mode for carrying out the present invention. It is the figure which showed the support | pillar which concerns on one Example of the backlight apparatus by this invention. It is the figure which showed the support | pillar which concerns on the other embodiment of the backlight apparatus by this invention. It is the figure which showed the support | pillar which concerns on the further another example of embodiment of the backlight apparatus by this invention. It is a figure where it uses for description of a prior art example. It is the figure which showed the state of the light of the support | pillar tip in a prior art example.

Explanation of symbols

30, 40, 50 ... columns, 41 ... transmission part, 42 ... non-transmission part, 51 ... strong transmission part, 52 ... weak transmission part, 100 ... liquid crystal display device, 140 ... backlight device, 141 ... diffusion plate

Claims (7)

In a column supporting an optical structure on which direct light and indirect light from a light source are incident,
A strut characterized in that a light-transmitting material is used for at least a part of a strut tip portion in contact with the optical structure. The strut according to claim 1, wherein a material that transmits light is used at least in a portion including a part of a tip end portion of the strut in contact with the optical structure, and a material that does not transmit light is used in other portions. The support column according to claim 2, wherein an upper part of the support column including a part of a support tip end portion in contact with the optical structure is made of a material that transmits light, and a lower part is made of a material that does not transmit light. The light transmitting material is used for at least a part of the column tip in contact with the optical structure, and a material having a light transmitting property lower than that of the light transmitting material is used for the other part. The support according to 1. The portion that is continuous with a part of the tip of the column in contact with the optical structure is a light-transmitting material, and the periphery of the part that is continuous with a part of the tip of the column is light-transmitting from the light-transmitting material. The support column according to claim 4, wherein the support column is made of a weak material. In a backlight device having a column supporting an optical structure on which direct light and indirect light from a light source are incident,
The backlight device is characterized in that a light-transmitting material is used for at least a part of a tip end portion of the column in contact with the optical structure. In a liquid crystal display device comprising a transmissive liquid crystal display panel and a backlight device in which a plurality of light sources are arranged to illuminate the liquid crystal display panel from the back side,
The backlight device includes a support column that supports an optical structure to which direct light and indirect light from the light source are incident, and the support column transmits light to at least a part of a support column tip in contact with the optical structure. A liquid crystal display device characterized by using a material having a characteristic.

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