JP2006227423A - Backlight apparatus and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin type liquid crystal display whose color unevenness and luminance unevenness are reduced. <P>SOLUTION: A backlight apparatus 140 includes a light source comprising a plurality of light emitting diodes 21 respectively emitting at least red color light, green color light and blue color light, a light guide plate 30 covering the light emission direction of the plurality of light emitting diodes 21 to be the light source and controlling radiation angle distribution of the color light emitted from the respective light emitting diodes 21 and a diffusion plate 141 diffusing the color light emitted from the light guide plate 30 to emit the color light in a face shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display (LCD) including a backlight device, and more particularly to a backlight device that is reduced in thickness while reducing color unevenness, and a liquid crystal display device including the backlight device.

  Instead of CRT (Cathode Ray Tube), which has been used for many years since the start of television broadcasting, it has been made very thin, such as a liquid crystal display (LCD) and a plasma display (PDP). Television receivers have been devised and put into practical use. In particular, liquid crystal display devices using a liquid crystal display panel can be driven with low power consumption, and it is considered that the liquid crystal display device will be used at an accelerated pace due to the price reduction of large liquid crystal display panels. It is a display device that can be expected to develop further.

  In the liquid crystal display device, a backlight method in which a color image is displayed by illuminating a transmissive liquid crystal display panel provided with a color filter from the back side with a backlight device is mainly used. As a light source of a backlight device, a fluorescent lamp such as a CCFL (Cold Cathode Fluorescent Lamp) that emits white light using a fluorescent tube is often used.

  In addition, since the CCFL encloses mercury in a fluorescent tube and thus has an adverse effect on the environment, a light emitting diode (LED) is promising as a light source of a backlight device that replaces the CCFL (for example, Patent Document 1).

  With the development of blue light-emitting diodes, light-emitting diodes that emit red, green, and blue light, which are the three primary colors of light, have been prepared, and red light, green light, and blue light emitted from these light-emitting diodes have been prepared. By mixing colors, 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 of the color light via the liquid crystal display panel is increased, so that the color reproduction range can be greatly expanded compared with the CCFL.

  As a light-emitting diode used as a light source of a backlight device, a light-emitting diode using a high-power light-emitting diode (LED) chip is effective. By using this light-emitting diode, the luminance of the backlight device is greatly improved. Can do.

Japanese Patent Laid-Open No. 7-191311

  Backlight devices that emit illumination light for illuminating a liquid crystal display panel are roughly classified into two types, a direct type and an edge light type, depending on the arrangement position of the light source. The direct type is a backlight device in which a light source is arranged directly under the back side of the liquid crystal display panel, and the side edge type is a light guide plate that guides light directly under the back side of the liquid crystal display panel. This is a type of backlight device in which a light source is disposed on the side surface of the backlight device.

  Compared to the edge light type backlight device, the direct type backlight device does not require a light guide plate, so the number of parts is reduced and the manufacturing cost can be reduced. In particular, when a CCFL is used as a light source, the CCFL itself emits white light, so that the backlight device does not require a thickness for color mixing, and thus a very thin liquid crystal display device can be configured. it can.

  However, when a light emitting diode that emits red light, green light, and blue light, which are the three primary colors of light, is used as the light source of the backlight device, in order to mix these three primary color lights into white light, a liquid crystal display is used. It is necessary to secure a sufficient distance to the diffusion plate arranged in front of the panel.

  Specifically, since the light emitting diodes that emit the three primary colors are each packaged, even if they are collected and arranged in one place in order to improve color mixing, the emitted three primary colors are emitted on the diffusion plate. In this case, the colors are not completely mixed, and the closer the distance to the diffusion plate, the more prominent it becomes. When the liquid crystal display panel is illuminated using white light with uneven color, which is insufficiently mixed with the three primary colors, as illumination light, the image displayed on the liquid crystal display panel also becomes an image in which color expression is not appropriately performed.

  Therefore, in order to widen the color reproduction range, if a light emitting diode that emits three primary colors is used as a light source and a direct type backlight device is configured, it is necessary to increase the thickness of the backlight device, which obstructs thinning of the liquid crystal display device. Will end up.

  In addition, if the backlight device is given a thickness and sufficient space for diffusion is not secured, the light emitted from the light-emitting diodes is not diffused throughout the backlight device, and the brightness at the position immediately above the light-emitting diodes is arranged. As a result, the luminance becomes uneven.

  Thus, the reduction in thickness of the backlight device and the suppression of color unevenness and brightness unevenness are in a trade-off relationship with each other, and it is very difficult to solve both of them simultaneously.

  Therefore, the present invention has been devised to solve the above-described problems, and uses a light emitting diode that emits light of three primary colors to broaden the color reproduction range and to illuminate a liquid crystal display panel. An object of the present invention is to provide a backlight device that can reduce color unevenness and luminance unevenness and achieve a thin thickness, and a liquid crystal display device using the backlight device.

  To achieve the above object, a backlight device according to the present invention emits at least red light, green light, and blue light in a backlight device that illuminates a transmissive liquid crystal display panel with white light from the back side. A light source composed of a plurality of light emitting diodes, an optical member that covers the light emission direction of the plurality of light emitting diodes that are the light sources, and that controls the emission angle distribution of the colored light emitted from each of the light emitting diodes; And a diffusion plate for diffusing the colored light and emitting planar light.

  In order to achieve the above object, a liquid crystal display device according to the present invention is a liquid crystal display device comprising a transmissive liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel with white light from the back side. The backlight device covers a light emission direction of a plurality of light emitting diodes that emit at least red light, green light, and blue light, and a plurality of light emitting diodes that are the light sources, and is emitted from each of the light emitting diodes. And an optical member for controlling the emission angle distribution of the colored light, and a diffusion plate for diffusing the colored light emitted from the optical member to emit a planar light.

  The present invention controls the radiation angle distribution of red light, green light, and blue light emitted from a red light emitting diode, a green light emitting diode, and a blue light emitting diode by providing an optical member such as a diffusion plate and an optical block. Is uniformly diffused over the entire surface of the liquid crystal display panel.

  Therefore, when the liquid crystal display panel is illuminated with illumination light emitted from such a backlight device, an image with good color reproducibility can be displayed on the liquid crystal display panel. In addition, since the backlight device does not require a space necessary for color mixing with white light, the backlight device can be made much thinner than a conventional direct type backlight device. That is, it is possible to reduce color unevenness and brightness unevenness and provide a thin liquid crystal display device with high color reproducibility.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following examples, It cannot be overemphasized that it can change arbitrarily in the range which does not deviate from the summary of this invention.

  The present invention is 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 that processes a video signal and an audio signal received by the receiving unit, respectively. An audio signal output unit such as a speaker that outputs an audio signal processed by the signal processing unit, the audio signal processing unit, and the audio signal processing unit 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. And a TFT substrate 111 and a counter electrode substrate 112 are sandwiched between two polarizing plates 131 and 132. 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. The transmissive color liquid crystal display device 100 drives the transmissive color liquid crystal display panel 110 having such a configuration in an active matrix system in a state where white light is irradiated from the back side by the backlight device 140. 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 sufficiently diffuses light sources not shown here and light emitted from the light sources so as to suppress color unevenness and luminance unevenness while maintaining light use efficiency. In the backlight housing unit 120 in which the function to be performed is incorporated, the diffusion plate 141, the optical sheet group 145 such as the diffusion sheet 142, the prism sheet 143, and the polarization conversion sheet 144 arranged on the diffusion plate 141 are arranged. It has a configuration with.

  The diffusing plate 141 makes the luminance emitted from the surface emission uniform by internally diffusing the light emitted from the light source.

  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, the backlight housing 120 includes a plurality of red light emitting diodes 21R that emit at least red light, green light emitting diodes 21G that emit green light, and blue light emitting diodes 21B that emit blue light. The light emitting diode unit 21 _n (n is a natural number) is used as a light source. In the following description, the red light emitting diode 21R, the green light emitting diode 21G, and the blue light emitting diode 21B are collectively referred to as the light emitting diode 21.

For example, as shown in FIG. 3, the light emitting diode units 21 _n have a longitudinal direction parallel to the horizontal direction of the backlight housing 120 and are arranged in a plurality of rows in the vertical direction in the backlight housing 120.

  A light guide plate 30 is provided in the backlight casing 120 so as to cover the light emitting diode 21. FIG. 4 shows a schematic cross-sectional view of the transmissive color liquid crystal display device 100 assembled by cutting along the XX line attached to the transmissive color liquid crystal display device 100 shown in FIG.

  As shown in FIG. 4, the light guide plate 30 is formed with a recess 31 for storing the light emitting diode 21 on the backlight housing 120 side where the light emitting diode 21 is disposed. The light guide plate 30 is formed of, for example, an acrylic resin.

  The concave portion 31 formed in the light guide plate 30 stores the light emitting diode 21 so as to cover the light emitting direction of the light emitting diode 21, so that each color light emitted from the light emitting diode 21 is incident on the light guide plate 30. become. The light guide plate 30 is an optical member provided to reduce the thickness of the backlight device 140. The light guide plate 30 is a front stage that reaches the diffusion plate 141 by making each color light emitted from the light emitting diode 21 enter and diffuse internally. The color mixture of each color light and the luminance distribution are made good.

  The inner wall surface 120a of the backlight housing 120 is a reflective surface that is subjected to reflection processing in order to increase the utilization efficiency of the light emitted from the light emitting diode 21.

  The colored light incident on the light guide plate 30 is internally diffused while being totally reflected in the light guide plate 30 and guided in the light guide plate 30. At this time, only the light component having a critical angle or less out of the color light incident on the light emitting surface 30 a is emitted to the diffusion plate 141. At this time, the amount of light emitted to the diffusion plate 141 can be controlled by providing an appropriate diffusion surface on the light guide plate. By using such a light guide plate 30, light spreads throughout the backlight housing 120, that is, the entire surface of the liquid crystal display panel 110 in front of the diffusion plate 141, so that the distance between the light emitting diode 21 and the diffusion plate 141 is shortened. Therefore, the backlight device 140 can be thinned.

  The light incident surface 31A, which is the side wall surface of the recess 31 formed in the light guide plate 30, has, for example, a curved shape, and the color light emitted from the light emitting diode 21 and entering the light guide plate 30 The ratio of passing through the light plate 30 and directly exiting from the light exit surface 30a is reduced.

  Although the light emitting diode 21 is not described in detail, each light emitting bulb is held by a resin holder, and a pair of terminals protrude from the resin holder. Each light emitting diode 21 is provided with an optical component 21a that emits light emitted from the light source from the side surface, that is, has a directivity for emitting the main component of the emitted light in the outer peripheral direction of the light emitting bulb. So-called side emission type LEDs are used. The side-emitting LED is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2003-8068 and 2004-133391.

  FIG. 5A schematically shows the state of light emitted from the light emitting diode 21, and FIG. 5B shows the radiation angle distribution of light emitted from the light emitting diode 21. As shown in FIG. 5A, the light emitted from the light emitting diode 21 is emitted at a predetermined controlled emission angle. As shown in FIG. 5B, it can be seen that the light emitting diode 21 which is a side emission type LED has the largest amount of light components emitted at an emission angle of about 80 degrees.

  Thus, unlike the so-called bullet-type LED having general radiation characteristics, the side emission type LED is installed in the backlight casing 120 without emitting the emitted light directly above. In this case, the light can be spread over a wide range in the housing.

  However, as can be seen from FIG. 5B, since the emission angle is not completely 90 degrees, even if it is incident on the light guide plate 30, it is transmitted through the light guide plate 30 without being internally diffused, and is emitted as it is. There is also a component of light emitted from the surface 30a. For example, since the refractive index of the light guide plate 30 formed of acrylic resin or the like is higher than the refractive index of air, the light emitted from the light emitting diode 21 and incident on the light guide plate 30 is light when entering the light guide plate 30. The light is refracted so as to have an emission angle smaller than an incident angle with respect to a normal line standing on the incident surface.

  As shown in FIG. 6, if the light incident surface 31A of the recess 31 formed in the light guide plate 30 is perpendicular to the light emitting surface 30a, the light incident on the light incident surface 31A is For example, in the region F, the light incident on the light incident surface 30a is not more than the critical angle from the beginning, and is totally reflected by the light emitting surface 30a. It is emitted without. Since such light components are not sufficiently diffused, they appear as color unevenness and luminance unevenness when visually recognized.

  However, in order to improve the radiation angle distribution, it is very difficult to redesign the optical component 21a that determines the radiation angle distribution of the side emission type LED, which leads to an increase in cost. The radiation angle distribution is controlled by adjusting the shape of the incident surface 31A.

  For example, the shape of the light incident surface 31A of the recess 31 is a curved surface. The curved surface shape of the light incident surface 31A is such that the light emitted from the light emitting diode 21 is transmitted through the light guide plate 30 and the light component directly incident on the diffusion plate 141 is reduced according to the emission angle. It is shaped to be refracted.

  The shape of the light incident surface 31A of the recess 31 is not limited to a curved surface shape as shown in FIG. 7, but may be a shape formed by a plurality of planes as shown in FIG. 8, for example. Also in this case, as described above, the shape of the light incident surface 31A is such that the light emitted from the light emitting diode 21 is directly incident on the diffusion plate 141 through the light guide plate 30 according to the emission angle. The shape is refracted to reduce the light component.

  In this way, by using the light guide plate 30 provided with the recess 31 for storing the light emitting diode 21 in the backlight housing 120, the emission angle of the light emitting diode 21 is adjusted by adjusting the shape of the light incident surface 31 </ b> A of the recess 31. Distribution can be easily controlled. The light incident surface 31A is shaped to refract the light emitted from the light emitting diode 21 so that the light component that is transmitted through the light guide plate 30 and directly incident on the diffusion plate 141 is reduced. Since the light component guided while totally reflecting in the light guide plate 30 is increased, it is possible to reduce luminance unevenness and color unevenness even though the backlight device 140 is thin.

  Instead of the light guide plate 30 described above, the radiation angle distribution of the light emitting diode 21 is controlled using a plurality of optical blocks 40 prepared for the light emitting diode 21 on a one-to-one basis as shown in FIGS. You can also. Similar to the light guide plate 30, the optical block 40 is formed of, for example, acrylic resin, and is formed with a recess 41 that individually stores the light emitting diodes 21. The shape of the light incident surface 41A of the concave portion 41 that receives the light emitted from the light emitting diode 21 is emitted from the light emitting diode 21 in the same manner as the shape of the light incident surface 31A of the concave portion 30 formed on the light guide plate 30. The light is refracted so as to reduce the component of light that passes through the optical block and is directly incident on the diffusion plate 141 according to the emission angle.

  When the optical block 40 is used, since the material to be used can be reduced rather than forming the light guide plate 30 described above, the larger the color liquid crystal display device 100 is, the more advantageous in terms of cost and weight reduction. However, since it is necessary to attach the optical blocks 40 as many as the number of the light emitting diodes 21, it is more advantageous to use the light guide plate 30 in terms of simplicity of the assembly process.

  Moreover, although the light guide plate 30 and the optical block 40 are formed by injection molding with an acrylic resin, the shapes of the concave portions 31 and the concave portions 41 may make injection molding difficult. Therefore, an optical block 50 as shown in FIG. 11 can be considered. Similarly to the light guide plate 30 and the optical block 40, the optical block 50 controls the emission angle component of the light emitted from the light emitting diode 21, and the light emitted from the light emitting diode 21 is changed according to the emission angle. The light can be refracted so as to reduce the component of light directly incident on the diffusion plate 141.

  The optical block 50 is formed with a recess 51 for storing the light emitting diode 21. The light incident surface 51A on which the light emitted from the light emitting diode 21 is incident has a flat shape. Only refraction as shown in FIG. 6 is given to the outgoing angle of the emitted light.

  The optical block 50 has, for example, a curved surface shape such that the light emitting surface 51B has the same effect as the light guide plate 30, the light incident surface 31A of the optical block 40, and the light incident surface 41A. The light exit surface 51B reduces the light component directly incident on the diffuser plate 141 according to the incident angle to the light exit surface 51B from the light emitted from the light emitting diode 21 and guided through the optical block 50. The shape is made to be refracted.

  The optical block 50 has a shape most suitable for injection molding, and can be molded very easily as compared with the light guide plate 30 and the optical block 40.

  Thus, using the optical block 40 provided with the concave portion 41 or the optical block 50 provided with the concave portion 51 so as to store the light emitting diode 21 in the backlight housing portion 120, the shape of the light incident surface 41A of the concave portion 41 is used. Alternatively, the radiation angle distribution of the light emitting diode 21 can be easily controlled by adjusting the shape of the light emitting surface 51B. The shape of the light incident surface 41A or the light emitting surface 51B is reduced by refracting the light emitted from the light emitting diode 21 so that the light component directly incident on the diffusion plate 141 is reduced. Even with the backlight device 140, it is possible to reduce luminance unevenness and color unevenness.

  The transmissive color liquid crystal display device 100 having such a configuration is driven by a drive circuit 200 as shown in FIG. 12, for example. The driving circuit 200 includes a color liquid crystal display panel 110, a power supply unit 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 an image supplied from the outside. RGB process processing unit 250 to which a signal and a video signal received by a receiving unit (not shown) included in transmission type color liquid crystal display device 100 and processed by a video signal processing unit are supplied via input terminal 240, An image memory 260 and a control unit 270 connected to the RGB process 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 the RGB separate supplied to the X driver circuit 220 via the image memory 260. By driving the color liquid crystal display panel 110 with a 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 included in the optical unit 21 _mn 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 a receiving unit (not shown) described above, adjusts an audio output amount to be output by an audio output unit (not shown), or from a 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.

  As described above, the backlight device 140 converts the radiation angle distribution of the red light, the green light, and the blue light emitted from the red light emitting diode 21R, the green light emitting diode 21G, and the blue light emitting diode 21B to the light guide plate 30, the optical block 40, or Control is performed by providing an optical member such as the optical block 50, and the light is uniformly diffused over the entire surface of the liquid crystal display panel 110 before being incident on the diffusion plate 141.

  Therefore, when the liquid crystal display panel 110 is illuminated with illumination light emitted from such a backlight device 140, an image with good color reproducibility can be displayed on the liquid crystal display panel 110. Further, since the backlight device 140 does not require a space necessary for color mixing with white light, the backlight device 140 can be made thinner than a conventional direct type backlight device. That is, a thin color liquid crystal display device with high color reproducibility can be realized.

It is a disassembled perspective view which shows typically the principal part structure of the color liquid crystal display device to which this invention is applied. It is a figure which shows the structure of the color filter provided in the liquid crystal display panel with which the same color liquid crystal display device was equipped. It is a typical perspective view which shows schematic structure of the backlight apparatus for liquid crystal displays with which the same color liquid crystal display device was equipped. It is a longitudinal cross-sectional view at the time of cut | disconnecting a color liquid crystal display device by the XX line shown in FIG. In the side emission type light emitting diode, (a) is a diagram schematically showing an emission direction, and (b) is a diagram showing a radiation angle distribution. It is the figure which showed the mode of refraction | bending in the light-incidence surface when making the light-incidence surface of the recessed part provided in the light-guide plate into a plane. It is the figure which showed the mode of refraction | bending in the light-incidence surface when making the light-incidence surface of the recessed part provided in the light-guide plate into a curved surface shape. It is the figure which showed the mode of refraction | bending at the light-incidence surface when making the light-incidence surface of the recessed part provided in the light-guide plate into another shape according to the said curved surface shape. It is a figure for demonstrating the case where it replaces with a light-guide plate and uses an optical block. It is the figure which showed the mode of refraction | bending at the light-incidence surface at the time of using an optical block. It is the figure which showed the mode of refraction | bending at the light-projection surface at the time of using another optical block. It is a block diagram which shows the structure of the drive circuit which drives the said color liquid crystal display device.

Explanation of symbols

21R red (R) light emitting diode, 21G green (G) light emitting diode, 21B blue (B) light emitting diode, 21 _n (n is a natural number) light emitting diode unit, 30 light guide plate, 30a light emitting surface, 31, 41, 51 recess , 31A, 41A, 51A Light incident surface, 40, 50 optical block, 51B Light emission surface, 140 Liquid crystal display backlight device

Claims (14)

In a backlight device that illuminates a transmissive liquid crystal display panel with white light from the back side,
A light source composed of a plurality of light emitting diodes each emitting at least red light, green light, and blue light;
An optical member that covers the light emission direction of the plurality of light emitting diodes as the light source, and controls the emission angle distribution of the colored light emitted from each of the light emitting diodes;
A backlight device, comprising: a diffusion plate that diffuses the color light emitted from the optical member to emit planar light. The optical member is a light guide plate having a plurality of recesses for storing the light emitting surfaces of a plurality of light emitting diodes which are the light sources, and having a light diffusion surface on the diffusion plate side. The backlight device according to claim 1. Each recess formed in the light guide plate refracts light so as to reduce the proportion of the color light directly incident on the diffusion surface of the light guide plate out of the color light incident on the light guide plate from the light emitting diode. The backlight device according to claim 2, further comprising a surface. 2. The backlight device according to claim 1, wherein the optical member is a plurality of optical blocks in which concave portions are formed so as to cover the light emitting surfaces of the respective light emitting diodes that are the light sources. Each concave portion formed in the optical block reduces the proportion of the color light that is transmitted from the light emitting diode and incident on the optical block and is directly incident on the diffuser plate. The backlight device according to claim 4, further comprising a light incident surface to be refracted. Each concave portion formed in the optical block reduces the proportion of the color light that is transmitted from the light emitting diode and incident on the optical block and is directly incident on the diffuser plate. The backlight device according to claim 4, further comprising a light exit surface to be refracted. The backlight device according to claim 1, wherein the light emitting diode is a side emission light emitting diode provided with an optical component that emits light emitted from a light source from a side surface. In a liquid crystal display device comprising a transmissive liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel with white light from the back side,
The backlight device includes a light source including a plurality of light emitting diodes that emit at least red light, green light, and blue light, respectively.
An optical member that covers the light emission direction of the plurality of light emitting diodes as the light source, and controls the emission angle distribution of the colored light emitted from each of the light emitting diodes;
A liquid crystal display device comprising: a diffusion plate that diffuses the color light emitted from the optical member to emit planar light. The optical member is a light guide plate having a plurality of recesses for storing the light emitting surfaces of a plurality of light emitting diodes which are the light sources, and having a light diffusion surface on the diffusion plate side. The liquid crystal display device according to claim 8. Each recess formed in the light guide plate refracts light so as to reduce the proportion of the color light directly incident on the diffusion surface of the light guide plate out of the color light incident on the light guide plate from the light emitting diode. The liquid crystal display device according to claim 9, further comprising a surface. 9. The liquid crystal display device according to claim 8, wherein the optical member is a plurality of optical blocks in which concave portions are formed so as to cover a light emitting surface of each light emitting diode as the light source. Each concave portion formed in the optical block reduces the proportion of the color light that is transmitted from the light emitting diode and incident on the optical block and is directly incident on the diffuser plate. The liquid crystal display device according to claim 11, further comprising a light incident surface to be refracted. Each concave portion formed in the optical block reduces the proportion of the color light that is transmitted from the light emitting diode and incident on the optical block and is directly incident on the diffuser plate. The liquid crystal display device according to claim 11, further comprising a light exit surface that is refracted. The liquid crystal display device according to claim 8, wherein the light emitting diode is a side emission light emitting diode provided with an optical component that emits light emitted from a light source from the side surface.

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