JP2015201366A - Backlight device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit variations of luminance distribution with a simple structure.SOLUTION: Multiple light emitting bars 60 are arranged parallel to each other and emit light L10 to a display panel 11. Each light guide plate 72 is disposed between the multiple light emitting bars 60. The light guide plate 72 is formed so that light L20 emitted by a light source 70 is headed to the display panel 11.

Description

  The present invention relates to a backlight device that emits light to a display panel that displays an image using light, and an image display device including the backlight device.

  The liquid crystal panel included in the video display device does not emit light by itself. Therefore, the video display device generally includes a backlight device that emits light used by the liquid crystal panel to display the video. The backlight device is provided to emit light to the back surface of the liquid crystal panel.

  Conventionally, a cold cathode fluorescent lamp (CCFL (Cold Cathode Fluorescent Lamp)) has been mainly used as a light source of a backlight device. However, in recent years, with the dramatic improvement in performance of light emitting diodes (LEDs), the demand for backlight devices using LEDs as light sources is rapidly increasing.

  There are roughly two types of light sources using LEDs (hereinafter also referred to as LED light sources). One type of LED light source is an LED that emits monochromatic light (hereinafter also referred to as a monochromatic LED). The monochromatic light is red light, green light, blue light, or the like. The other type of LED light source is a light source (hereinafter also referred to as a multicolor LED light source) composed of a single color LED and a phosphor. In the multi-color LED light source, the phosphor is excited by the light emitted from the monochromatic LED, thereby obtaining light of a plurality of types.

  The multicolor LED light source includes, for example, a monochromatic LED that emits blue light and a phosphor. In the multicolor LED light source, the phosphor emits green to red light using the blue light emitted from the monochromatic LED. The multicolor LED light source is a light source that emits white light having a broad spectrum from blue light to red light (hereinafter also referred to as a white LED light source) depending on the configuration of the phosphor. The white LED light source has high luminous efficiency and is effective in reducing power consumption. Therefore, white LED light sources are widely used as light sources for backlight devices.

  A liquid crystal panel included in the video display device includes a color filter. The video display device performs color expression by extracting only light in the spectral range of red, green, and blue wavelengths using the color filter. In a light source having a continuous spectrum with a wide wavelength band, such as a white LED light source, the wavelength band of light transmitted through the color filter of the video display device is set narrow in order to widen the color reproduction range. Thereby, the color purity of the light which a video display device radiate | emits is raised.

  However, if the wavelength band of light transmitted through the color filter is set to be narrow, the amount of light that becomes unnecessary increases. For this reason, the light use efficiency in the liquid crystal panel becomes very poor. This causes a reduction in the luminance of the display surface of the liquid crystal panel. Moreover, in order to improve the brightness | luminance of a display surface, it is necessary to increase the electric current supplied to LED, for example. In this case, the power consumption of the video display device increases.

  Generally used CCFL and white LED light sources are configured to emit light having an emission spectrum in which the wavelength peak is about 615 [nm] in the red wavelength range due to the characteristics of the phosphor. . The wavelength of about 615 [nm] is a wavelength in which the red wavelength is shifted to the orange wavelength.

  For this reason, in particular, when the color purity of the light is increased at 630 to 640 [nm], which is preferable as a wavelength region of pure red light, the amount of transmitted light is extremely reduced. As a result, the brightness of the light is significantly reduced.

  Further, in the CCFL, the white LED light source, and the like, the energy amount of the spectrum of red light is small particularly in the wavelength range of 600 to 700 [nm]. For this reason, when the color purity of the light is increased at 630 to 640 [nm], which is preferable as the wavelength region of pure red light, the amount of transmitted light is extremely reduced. As a result, the brightness of the light is significantly reduced.

  In order to expand the color reproduction range while minimizing light loss due to the color filter, it is necessary to employ a light source that emits light with a narrow wavelength bandwidth. That is, in order to widen the color reproduction range, it is necessary to employ a light source that emits light with high color purity.

  Therefore, in recent years, an image display device using three single-color LEDs that emit light of three primary colors such as red light, green light, and blue light has been proposed. In addition, an image display apparatus using three monochromatic lasers that emit light of three primary colors has been proposed. A monochromatic laser is a laser that emits laser light of one color. In these video display devices, light of three primary colors is mixed to generate white light.

  That is, in recent years, in order to widen the color reproduction range, an image display device having a backlight device using a single color LED, a single color laser, or the like that emits light with a narrow wavelength width as a light source has been proposed. “Narrow wavelength range” means high color purity. In particular, lasers have very good monochromaticity. For this reason, a video display device using a single color LED, a single color laser, or the like can provide an image with a wide color reproduction range and high brightness. In addition, an image display device using a single color LED, a single color laser, or the like can reduce power consumption.

  However, in a configuration in which light emitted from each of these light sources is mixed to generate white light, a difference in luminance distribution on the display surface of the liquid crystal panel corresponding to the light of each color appears as color unevenness. In order to reduce the color unevenness, it is required to improve the uniformity of the luminance distribution on the display surface corresponding to the light of each color.

  However, light emitted from light sources having different light emission principles and material characteristics of the light emitting element has different divergence angles, light emission efficiencies, and the like. For this reason, the number and arrangement method of each light source are different for each characteristic. For these reasons, it is necessary to provide an optimum means for making the luminance distribution in the display surface uniform for each light source.

  In other words, when a point light source such as an LED or a laser is adopted as the light source of the backlight device, the luminance in the vicinity of the light source is remarkably increased. As a result, uneven brightness occurs in the vicinity of the end of the component where high brightness light is incident from the backlight device. Such luminance unevenness can be improved, for example, by arranging a large number of point light sources in a line at a narrow interval so as to be close to the linear light source.

  However, a backlight device of a video display device that requires high uniformity of luminance distribution in the display surface requires a large number of light sources. In particular, the divergence angle of laser light in the semiconductor laser is ¼ or less of the divergence angle of light in the LED. Therefore, a backlight device that uses a semiconductor laser as a light source requires a large number of light sources. As a result, when a large number of light sources are used, an increase in power consumption, a decrease in assemblability, an increase in cost, and the like occur.

  In a configuration using LEDs, a technique for making the luminance distribution in the display surface uniform with as few light sources as possible is required. For example, Patent Document 1 discloses a technique (hereinafter also referred to as related technique A) that makes the luminance distribution in the irradiated region uniform. Specifically, in Related Art A, a lens disposed on a light emitting side of a point light source such as an LED widens the radiation angle of the light emitted from the LED, and forms a uniform surface light source. It is a lens for. In other words, in Related Art A, the radiation angle of the light emitted from the LED is expanded by the refractive effect of the lens. Thereby, luminance unevenness and the like are reduced. That is, the luminance distribution in the irradiated region (for example, the display surface of the liquid crystal panel) is made uniform.

  Patent Document 2 discloses a technique (hereinafter also referred to as related technique B) that uses a light guide plate to make the luminance distribution uniform. Specifically, in Related Technology B, in a region between a plurality of fluorescent tubes arranged in parallel to each other, a plurality of LEDs are arranged in a row in the length direction of the fluorescent tube. The plurality of LEDs are covered with a light guide plate from the light emission side of the plurality of LEDs. The light guide plate has a function of converting light from the LED into a surface light source on the surface of the diffusion plate. With this configuration, color unevenness can be reduced.

  Further, Patent Document 3 discloses a technique (hereinafter also referred to as related technique C) for making the luminance distribution uniform by providing a light guide plate for each light source having different characteristics. Specifically, in Related Technology C, a dedicated light guide plate suitable for the characteristics is provided for each light source having different characteristics. A light guide plate is provided for each light source that emits different color light. The plurality of light guide plates are stacked (stacked) in the thickness direction of the light guide plate.

  In Related Art C, white illumination light is generated by adding together monochromatic planar light emitted from each light guide plate. According to this configuration, the structure of each light guide plate can be optimized for the characteristics of one type of light source corresponding to the light guide plate. Therefore, according to this configuration, the uniformity of the in-plane luminance distribution for each color can be improved. As a result, color unevenness can be suppressed.

Japanese Patent No. 4628302 JP 2009-110860 A JP-A-6-138458

  However, the related technologies A, B, and C have the following problems. Specifically, the related technique A is a technique using a point light source. For this reason, in Related Art A, in order to suppress variations in luminance distribution on the display surface, it is necessary to have a complicated configuration in which a large number of point light sources are provided. In this case, there is a problem that the manufacturing cost becomes high.

  In Related Art B, in order to suppress variations in the luminance distribution on the display surface, it is necessary to arrange a plurality of LED groups each composed of a plurality of LEDs arranged in a row at a narrow interval. For this reason, in order to suppress variations in luminance distribution, it is necessary to have a complicated configuration with a very large number of light sources. In this case, there is a problem that the manufacturing cost becomes high.

  In Related Art C, a dedicated light guide plate suitable for the characteristics is provided for each light source having different characteristics. The plurality of light guide plates are overlapped in the thickness direction of the light guide plate. Therefore, the related technique C has a problem that the configuration is complicated and the manufacturing cost is high.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a backlight device and the like that can suppress variations in luminance distribution with a simple configuration.

  In order to achieve the above object, a backlight device according to one embodiment of the present invention emits light to a display panel that displays an image using light. The backlight device includes a plurality of elongated light emitting bars, each of the plurality of light emitting bars including a plurality of first light sources arranged in a line, and the plurality of light emitting bars are parallel to each other. The backlight device further includes: a second light source that emits second light; and a light guide plate that is disposed between the plurality of light emitting bars. The light guide plate is configured to direct the second light emitted from the second light source toward the display panel.

  According to the present invention, the plurality of light emitting bars are arranged in parallel to each other and emit the first light to the display panel. The light guide plate is disposed between the plurality of light emitting bars. The light guide plate is configured to direct the second light emitted from the second light source toward the display panel.

  That is, a light guide plate that directs the second light emitted from the second light source toward the display panel is disposed between the plurality of light emitting bars. That is, it is possible to suppress variations in the luminance distribution in the display panel region corresponding to the region between the plurality of light emitting bars only by adding the minimum necessary number of second light sources. Therefore, variation in luminance distribution can be suppressed by a simple configuration in which a light guide plate is disposed between the plurality of light emitting bars.

It is a top view which shows the structure of the video display apparatus concerning Embodiment 1 of this invention. It is sectional drawing of the video display apparatus concerning Embodiment 1 of this invention. It is a block diagram which shows the structure of the video display apparatus concerning Embodiment 1 of this invention. It is a top view which shows the structure of the backlight apparatus which concerns on Embodiment 1 of this invention. It is sectional drawing of the backlight apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the detailed structure of a light-guide plate. It is a top view which shows the structure of the backlight apparatus which is a part of video display apparatus concerning Embodiment 2 of this invention. It is sectional drawing of the backlight apparatus which is a part of video display apparatus concerning Embodiment 2 of this invention. It is a top view which shows the structure of the backlight apparatus which is a part of video display apparatus concerning Embodiment 3 of this invention. It is sectional drawing of the backlight apparatus which is a part of video display apparatus concerning Embodiment 3 of this invention. It is a top view which shows the structure of the backlight apparatus which concerns on a comparative example. It is sectional drawing of the backlight apparatus which concerns on a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof may be omitted.

  It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the constituent elements exemplified in the embodiments are appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to those examples. Moreover, the dimension of each component in each figure may differ from an actual dimension.

<Embodiment 1>
FIG. 1 is a plan view showing a configuration of a video display apparatus 1000 according to Embodiment 1 of the present invention. In FIG. 1, the X, Y, and Z directions are orthogonal to each other. The X, Y, and Z directions shown in the following figures are also orthogonal to each other. Hereinafter, a direction including the X direction and the direction opposite to the X direction (−X direction) is also referred to as an X-axis direction. In the following, the direction including the Y direction and the direction opposite to the Y direction (−Y direction) is also referred to as a Y-axis direction. In the following, a direction including the Z direction and a direction opposite to the Z direction (−Z direction) is also referred to as a Z-axis direction.

  Hereinafter, a plane including the X-axis direction and the Y-axis direction is also referred to as an XY plane. Hereinafter, a plane including the X-axis direction and the Z-axis direction is also referred to as an XZ plane. Hereinafter, a plane including the Y-axis direction and the Z-axis direction is also referred to as a YZ plane.

  FIG. 2 is a cross-sectional view of the video display apparatus 1000 according to Embodiment 1 of the present invention. Specifically, FIG. 2 is a cross-sectional view of the video display apparatus 1000 along the YZ plane of FIG. FIG. 3 is a block diagram showing a configuration of video display apparatus 1000 according to Embodiment 1 of the present invention.

  1, 2, and 3, video display apparatus 1000 includes display unit 110, sheet group 12, bezel 15, holding member 16, housing 17, electrical unit 20, and backlight. A device 200 and an input / output unit 30 are provided.

  Although described in detail later, the backlight device 200 emits light to the display unit 110. The backlight device 200 includes light sources 61 a and 70, coolers 202 a and 202 b, and an optical system 210. The light source 61a is an LED. The light source 61a is not limited to the LED, and may be another type of light source. The light source 70 is a semiconductor laser. The light source 70 is not limited to a semiconductor laser, and may be another type of light source.

  The coolers 202a and 202b cool the light source. In practice, the cooler 202a is provided to cool the light source 61a. The cooler 202b is provided to cool the light source 70.

  The optical system 210 includes a lens 61b, a substrate 62, and a light guide plate 72, which will be described later.

  The display unit 110 displays an image. Specifically, the display unit 110 includes a display panel 11 and a sheet group 12.

  The display panel 11 displays an image using light emitted from the backlight device 200. That is, the backlight device 200 emits light to the display panel 11. The display panel 11 is a liquid crystal panel, for example. The display panel 11 is not limited to a liquid crystal panel, and may be a panel of another type.

  The sheet group 12 is, for example, an optical member for imparting viewing angle characteristics and luminance distribution characteristics to the light emitted from the backlight device 200. The sheet group 12 includes a reflective polarizing sheet 12a, a prism sheet 12b, and a diffusion sheet 12c.

  The holding member 16 is a member that holds the sheet group 12. The bezel 15 holds the display panel 11 and the holding member 16. That is, the bezel 15 holds the sheet group 12 held by the holding member 16. The housing 17 houses, for example, the backlight device 200 and the like.

  The electrical unit 20 controls the backlight device 200 and the display unit 110. Specifically, the electrical unit 20 includes an image control board 21, a light source control board 22, a control board 23, and a power supply board 24.

  The image control board 21 controls the display panel 11 included in the display unit 110. The light source control board 22 controls light sources 61a and 70 described later. The control board 23 controls the image control board 21 and the light source control board 22. Power is supplied to the power supply board 24 from an external power supply P10. The power supply board 24 supplies the power supplied from the power supply P10 to the image control board 21, the light source control board 22, and the control board 23.

  The input / output unit 30 inputs and outputs data to the outside. The input / output unit 30 performs data communication with the control board 23. The input / output unit 30 includes an audio processing unit 31, a light receiving unit 32, an input / output I / F, and a recording medium 34.

  The sound processing unit 31 processes sound. The light receiving unit 32 receives an infrared signal from the remote control 32R. The infrared signal is a signal for controlling the infrared signal. The light receiving unit 32 transmits the received infrared signal to the control board 23.

  The input / output I / F is connected to an external device (not shown) by a communication cable. The recording medium 34 is a medium for recording data. The recording medium 34 is, for example, an HDD (Hard Disk Drive), a BD (Blu-ray Disc), or the like. Blu-ray Disc is a registered trademark.

  Next, a backlight device (hereinafter also referred to as a backlight device 200N) to be compared with the backlight device 200 will be described. The backlight device 200N is, for example, a backlight device used in a direct type liquid crystal television.

  FIG. 11 is a plan view showing a configuration of a backlight device 200N according to a comparative example. In FIG. 11, a diffusing plate 75 described later is shown in a transparent state for easy understanding of the configuration. FIG. 12 is a cross-sectional view of a backlight device 200N according to a comparative example. Specifically, FIG. 12 is a cross-sectional view of the backlight device 200N along the YZ plane of FIG. Hereinafter, the backlight device 200N will be briefly described.

  With reference to FIGS. 11 and 12, the backlight device 200 </ b> N includes a plurality of light emitting bars 60, a reflection sheet 74, and a diffusion plate 75. The plurality of light emission bars 60 are arranged at intervals along the Y-axis direction. Each light emitting bar 60 includes a plurality of light source portions 61 and a substrate 62. The plurality of light source units 61 are disposed on the substrate 62. Each light source unit 61 includes a light source 61a and a lens 61b. The light source 61a is an LED that emits white light.

  A detailed configuration of each component (for example, the light source 61a, the lens 61b, the diffusion plate 75, etc.) included in the backlight device 200N will be described later.

  Next, a detailed configuration of the backlight device 200 will be described. FIG. 4 is a plan view showing the configuration of the backlight device 200 according to Embodiment 1 of the present invention. FIG. 4 is also a diagram in which the bezel 15, the display panel 11, and the sheet group 12 are made transparent in the video display device 1000 of FIG. That is, the X direction and the Y direction in FIGS. 1 and 4 are the same direction. FIG. 5 is a cross-sectional view of backlight device 200 according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view of the backlight device 200 along the YZ plane of FIG.

  4 and 5, the backlight device 200 includes a plurality of light emitting bars 60, a reflection sheet 74, and a diffusing plate 75, similarly to the backlight device 200N.

  Each of the plurality of light emitting bars 60 has a long shape. The plurality of light emitting bars 60 are arranged in parallel to each other. Each of the plurality of light emission bars 60 includes a plurality of light sources 61a arranged in a line. Each light emitting bar 60 is provided such that the light emitting bar 60 emits light to the display panel 11. Hereinafter, the light emitted from the light emitting bar 60 (light source 61a) is also referred to as light L10.

  Specifically, each light emitting bar 60 includes a plurality of light source units 61 and a substrate 62. The shape of the substrate 62 is long. The plurality of light source units 61 are linearly arranged on the substrate 62. The plurality of light source units 61 may be arranged in a wave shape on the substrate 62.

  Each light source unit 61 includes a light source 61a and a lens 61b. That is, the plurality of light sources 61 a are arranged linearly on the substrate 62.

  The light source 61a is an LED that emits white light. The light source 61a emits light L10 radially in a direction (Z direction) orthogonal to the direction (X axis direction) in which the substrate 62 extends.

  The lens 61b is provided so as to cover the light source 61a. The lens 61b is a lens for diffusing the light emitted from the light source 61a. Specifically, the lens 61b refracts the light emitted from the light source 61a and expands the propagation direction of the light. With this lens 61b, the luminance distribution of the light applied to the display panel 11 is made closer to uniform.

  As described above, the plurality of light sources 61 a (light source unit 61) are linearly arranged on the substrate 62. Thereby, the luminance distribution of the light irradiated to the display panel 11 can be made more uniform.

  The reflection sheet 74 has a shape for accommodating the plurality of light emitting bars 60. The reflection sheet 74 is a sheet that reflects light. The reflection sheet 74 has a main surface 74s. The main surface 74 s is a surface corresponding to a portion of the reflective sheet 74 that is farthest from the diffusion plate 75. Although the details will be described later, the reflection sheet 74 reflects a part of the light emitted from the light emitting bar 60 and the light source 70 described later so as to go to the display panel 11. The diffusion plate 75 diffuses the light emitted from the light source unit 61 (light emitting bar 60).

  With reference to FIGS. 4 and 5, backlight device 200 further includes a plurality of light sources 70, a plurality of light guide plates 72, and a plurality of coolers 71.

  A plurality of light emitting bars 60, a plurality of light sources 70, and a plurality of light guide plates 72 are disposed on the main surface 74 s of the reflection sheet 74. That is, the light source 70 and the light guide plate 72 are disposed on the main surface 74s where the light emitting bar 60 is disposed. As described above, the main surface 74 s is a surface corresponding to a portion of the reflection sheet 74 that is farthest from the diffusion plate 75.

  Thereby, the distance from the light guide plate 72 to the diffusion plate 75 is set such that the light guide plate 72 is disposed at a position other than the main surface 74s (for example, an intermediate position between the diffusion plate 75 and the reflection sheet 74). Can be long. As a result, the luminance distribution of light applied to the display panel 11 can be made more uniform.

  The light source 70 is a semiconductor laser. The light source 70 emits light L20, which is laser light, radially.

  The cooler 71 is, for example, a heat sink. Semiconductor lasers are more susceptible to heat than LEDs. Therefore, a cooler 71 is thermally connected to each light source 70. Note that the backlight device 200 may not include the cooler 71.

  The shape of the light guide plate 72 is long. The light guide plate 72 is disposed between the plurality of light emitting bars 60. Specifically, the light guide plate 72 is disposed between two adjacent light emitting bars 60 among the plurality of light emitting bars 60. Although details will be described later, two light sources 70 are provided for one light guide plate 72.

  Although described in detail later, the light guide plate 72 is configured to direct the light L20 emitted from the light source 70 toward the display panel 11. Hereinafter, a detailed configuration of the light guide plate 72 will be described.

  FIG. 6 is a diagram for explaining a detailed configuration of the light guide plate 72. FIG. 6A is a plan view of the light guide plate 72. FIG. 6B is a side view of the long side of the light guide plate 72. In FIG. 6B, the reflection sheet 74 provided on the right side of the light guide plate 72 is not shown for easy understanding of the configuration. FIG. 6C is a side view of the light guide plate 72 on the short side. In FIG. 6C, the reflection sheet 74 provided on the lower side of the light guide plate 72 is not shown for easy understanding of the configuration.

  6A and 6B, only one of the two light sources 70 provided for one light guide plate 72 is shown for easy understanding of the configuration.

  Referring to FIGS. 4, 5 and 6, light guide plate 72 has light emitting surface 72s. The shape of the light emitting surface 72s in plan view (XY plane) is a rectangle. Hereinafter, a surface of the light guide plate 72 opposite to the light emitting surface 72s is also referred to as a back surface 72sa.

  A plurality of diffusion patterns 72 a are provided on the back surface 72 sa of the light guide plate 72. The plurality of diffusion patterns 72a are arranged in a matrix. The diffusion pattern 72a is a pattern for diffusing the light L20 irradiated to the diffusion pattern 72a. The diffusion pattern 72a is made of, for example, ink. The diffusion pattern 72a is printed on the back surface 72sa of the light guide plate 72, for example.

  Hereinafter, the side surface of the light guide plate 72 corresponding to the short side of the light emitting surface 72s is also referred to as an incident surface. The light guide plate 72 has two incident surfaces.

  The light source 70 is provided on the two incident surface sides of the light guide plate 72. The light source 70 emits light L <b> 20 to the incident surface of the light guide plate 72. That is, the light source 70 emits the light L20 in a direction parallel to the longitudinal direction (X-axis direction) of the light emitting bar 60.

  Thereby, the light L20 propagates to the inside of the light guide plate 72 via the incident surface. Although details will be described later, the light L20 propagated inside the light guide plate 72 is diffused by hitting the diffusion pattern 72a. The reflection sheet 74 reflects part of the light L20 so that part of the diffused light L20 travels toward the display panel 11.

  Specifically, the reflection sheet 74 reflects the irradiated light so that the light irradiated to the reflection sheet 74 of the diffused light L20 is directed to the display panel 11. Thereby, the light L20 is emitted from the light emitting surface 72s of the light guide plate 72. The light L20 emitted from the light emitting surface 72s reaches the diffusion plate 75. Then, the diffusion plate 75 emits the diffused light L20 to the display panel 11. That is, the light emitting surface 72s of the light guide plate 72 emits the light L20 to the display panel 11.

  As described above, the backlight device 200 emits the light L10 and the light L20. The display panel 11 displays an image using the light L10 and the light L20 emitted from the backlight device 200.

  Each diffusion pattern 72 a is set to a larger size as it is closer to the central portion in the longitudinal direction of the light guide plate 72. In other words, each diffusion pattern 72a is configured such that the longer the distance between the diffusion pattern 72a and the light source 70, the larger the size of the diffusion pattern 72a.

  In addition, among all the diffusion patterns 72a provided on the back surface 72sa of the light guide plate 72, the sizes of some of the diffusion patterns 72a arranged along the short direction (Y-axis direction) of the light guide plate 72 are the same size. Is set.

  Next, the light L20 propagated inside the light guide plate 72 will be described with reference to FIG. In FIG. 6, only one of the two light sources 70 provided for one light guide plate 72 is shown in order to make it easy to see the state of the light L <b> 20 propagating inside the light guide plate 72.

  As shown in FIGS. 6A, 6B, and 6C, the light L20 emitted from the light source 70 propagates into the light guide plate 72 through the incident surface. The light L20 inside the light guide plate 72 is reflected by the interface of the light guide plate 72 as shown in FIGS. 6 (a) and 6 (b). And light L20 irradiated to the area | region in which the diffusion pattern 72a was formed among the back surfaces 72sa which are the interfaces of the light-guide plate 72 is diffused. Thereby, a part of the diffused light L <b> 20 is directed to the reflection sheet 74. The reflection sheet 74 reflects a part of the irradiated light L20 so that a part of the light L20 irradiated to the reflection sheet 74 is directed to the display panel 11 (diffusing plate 75).

  As described above, each diffusion pattern 72a is set to a larger size as it is closer to the central portion of the light guide plate 72 in the longitudinal direction. In other words, each diffusion pattern 72a is configured such that the longer the distance between the diffusion pattern 72a and the light source 70, the larger the size of the diffusion pattern 72a.

  The light L20 incident on the inside of the light guide plate 72 has a large amount of light immediately after being incident. Therefore, since each diffusion pattern 72a is configured as described above, even if the size of the diffusion pattern 72a existing at the end of the light guide plate 72 is small, a large amount of light in the light L20 can be diffused. As a result, the reflection sheet 74 reflects the diffused light so that the diffused light travels toward the diffusion plate 75.

  As shown in FIGS. 6A and 6B, when the light L20 propagates through the light guide plate 72, diffusion and reflection are repeated, and the light quantity of the light L20 decreases. For this reason, the light guide plate 72 is required to emit light L20 having a light amount equivalent to the light amount of the light L20 immediately after entering the light guide plate 72. In order to satisfy this requirement, it is necessary to increase the size of the diffusion pattern 72a of the light guide plate 72 so that a large amount of light is diffused and reflected.

  By adjusting the size of the diffusion pattern 72 a of the light guide plate 72 based on the above principle, the amount of light L20 emitted from the light guide plate 72 can be adjusted in the longitudinal direction of the light guide plate 72.

  Further, as described above, among all the diffusion patterns 72a provided on the back surface 72sa of the light guide plate 72, the size of a part of the diffusion patterns 72a arranged along the short direction (Y-axis direction) of the light guide plate 72. Are set to the same size. Therefore, as shown in FIG. 6C, the light is emitted from the light guide plate 72 by a part of the diffusion pattern 72 a arranged along the short direction (Y-axis direction) of the light guide plate 72 and the reflection sheet 74. The amount of the light L20 is almost the same.

  As described above, according to the present embodiment, the plurality of light emission bars 60 are arranged in parallel to each other and emit light L10 to the display panel 11. The light guide plate 72 is disposed between the plurality of light emitting bars 60. The light guide plate 72 is configured to direct light L <b> 20 emitted from the light source 70 toward the display panel 11.

  That is, a light guide plate 72 that directs the light L20 emitted from the light source 70 toward the display panel 11 is disposed between the plurality of light emitting bars 60. That is, variation in luminance distribution in the area of the display panel 11 corresponding to the area between the plurality of light emitting bars 60 can be suppressed only by adding the minimum necessary number of light sources 70. Therefore, variation in luminance distribution can be suppressed by a simple configuration in which the light guide plate 72 is disposed between the plurality of light emitting bars 60.

  Further, according to the present embodiment, the backlight device 200 has two types of light sources, the light emission bar 60 and the light source 70. Each of the plurality of light sources 61a provided on the light emitting bar 60 is covered with a lens 61b. With this lens 61b, the luminance distribution of the light applied to the display panel 11 is made closer to uniform.

  A plurality of light sources 61 a are arranged linearly on the substrate 62. Thereby, the luminance distribution of the light irradiated to the display panel 11 can be made more uniform.

  The backlight device 200 has two types of light sources, a light source 61 a and a light source 70. Accordingly, the backlight device 200 can display an image with better color reproducibility on the display panel 11 than the backlight device 200N using one type of light source such as the light source 61a.

  The light source 70 that is a semiconductor laser emits laser light having higher directivity than the light source 61a that is an LED. Therefore, for example, it is difficult to expand the radiation angle of the laser light by an optical element such as the lens 61b. Moreover, the semiconductor laser has high light emission efficiency and high light output. For this reason, it is difficult to increase the number of the light sources 61a and improve the uniformity of the luminance distribution in the display panel 11.

  Therefore, the backlight device 200 of the present embodiment includes a light source 70 that emits light L20 in a direction parallel to the direction in which the diffusion plate 75 extends, in addition to the light source 61a that emits light in the direction toward the diffusion plate 75. use. The light L20 emitted from the light source 70 enters the light guide plate 72. The light guide plate 72 emits light L20 to the diffusion plate 75 by the action of the diffusion pattern 72a of the light guide plate 72 and the action of the reflection sheet 74.

  Thereby, the light L10 emitted from the light emitting bar 60 and the light L20 directed to the diffusion plate 75 by the action of the light guide plate 72 and the reflection sheet 74 can be applied to the display panel 11 via the diffusion plate 75. . As a result, in the configuration of the present embodiment, the luminance distribution of light applied to the display panel 11 can be made more uniform than the configuration using the backlight device 200N. That is, color unevenness in the display panel 11 can be reduced.

  Further, according to the present embodiment, the light guide plate 72 emits the light L20 to the diffusion plate 75 by the action of the diffusion pattern 72a of the light guide plate 72 and the action of the reflection sheet 74. The light L20 emitted from the semiconductor laser having higher directivity than the light L10 emitted from the LED can be easily diffused. Moreover, since the light guide plate 72 emits light L20 having a large radiation angle by providing the diffusion pattern 72a, the number of light sources 70 that emit light to the light guide plate 72 can be reduced.

  Further, according to the present embodiment, the light guide plate 72 is disposed between the plurality of light emitting bars 60. As a result, the light source 70, the light guide plate 72, and the like are added to the backlight device 200N without changing the structure of the components (for example, the light emitting bar 60) in the backlight device 200N. Can be manufactured. That is, with the backlight device 200 to which the light source 70 is added to the backlight device 200N, the laser light and the light emitted from the LED can be easily mixed. As a result, the video display device 1000 with improved color reproducibility can be manufactured more easily and cheaply than the video display device using the backlight device 200N using only the LED as the light source.

  According to the related techniques A and B described above, a lens (optical element) that forms a uniform surface light source by expanding the radiation angle of light emitted from the point light source is used. Thereby, the liquid crystal panel can be irradiated with light having a substantially uniform luminance distribution. However, such a lens has a complicated structure.

  Further, in a configuration using a point light source with high directivity such as a laser, a complicated lens having higher diffusibility is required. For this reason, there is a problem that such a lens (optical element) is not optimal when a laser is used.

  In Related Art C, a dedicated light guide plate suitable for the characteristics is provided for each light source having different characteristics. Thereby, it becomes possible to obtain a planar light source having a highly uniform luminance distribution in which color unevenness is suppressed. However, in the above configuration, there is a problem that the cost of the apparatus increases because it is necessary to stack a plurality of light guide plates.

  Therefore, since the present embodiment is configured as described above, each of the above problems can be solved.

<Embodiment 2>
Next, the backlight device 200A provided with a plurality of light sources 70 on the incident surface side of the light guide plate 72 will be described. Hereinafter, the video display apparatus according to Embodiment 2 is referred to as a video display apparatus 1000A.

  FIG. 7 is a plan view showing a configuration of a backlight device 200A which is a part of the video display device 1000A according to Embodiment 2 of the present invention. FIG. 8 is a cross-sectional view of a backlight device 200A that is a part of the video display device 1000A according to Embodiment 2 of the present invention. FIG. 8 is a cross-sectional view of the backlight device 200A along the YZ plane of FIG.

  7 and 8, video display device 1000A is different from video display device 1000 in FIG. 2 in that backlight device 200A is provided instead of backlight device 200. Since the other configuration of video display apparatus 1000A is the same as that of video display apparatus 1000, detailed description will not be repeated.

  The backlight device 200 </ b> A differs from the backlight device 200 shown in FIGS. 4 and 5 in that a plurality of light sources 70 are provided on one incident surface side of the light guide plate 72. Since the other configuration of backlight device 200A is the same as that of backlight device 200, detailed description will not be repeated.

  Specifically, as illustrated in FIGS. 7 and 8, in the backlight device 200 </ b> A, a plurality of light sources 70 are provided in association with each of the two incident surfaces of each light guide plate 72. That is, a plurality of light sources 70 that emit light L20 to each incident surface of each light guide plate 72 are provided.

  With the above configuration, a sufficient amount of light L20 can be emitted from the light guide plate 72 even when the light output of one light source 70 is weak.

  Even when the number of light sources 70 for each incident surface of the light guide plate 72 is increased, the arrangement of the light guide plates 72 is the same as that of the backlight device 200 of the first embodiment. That is, the light guide plate 72 is disposed between the light emitting bars 60. As a result, the same effect as in the first embodiment can be obtained.

  That is, the backlight device 200 </ b> A is manufactured by adding the light source 70, the light guide plate 72, and the like to the backlight device 200 </ b> N without changing the structure of the components (e.g., the light emitting bar 60) in the backlight device 200 </ b> N. can do. That is, the laser light and the light emitted from the LED can be easily mixed by the backlight device 200A with the light source 70 added to the backlight device 200N. As a result, the image display device 1000A with improved color reproducibility can be manufactured easily and inexpensively as compared with the image display device using the backlight device 200N using only the LED as the light source.

<Embodiment 3>
Next, the backlight device 200B further provided with a diffusion sheet will be described. Hereinafter, the video display device according to Embodiment 3 is referred to as a video display device 1000B.

  FIG. 9 is a plan view showing a configuration of a backlight device 200B which is a part of the video display device 1000B according to Embodiment 3 of the present invention. FIG. 10 is a cross-sectional view of a backlight device 200B that is a part of a video display device 1000B according to Embodiment 3 of the present invention. FIG. 10 is a cross-sectional view of the backlight device 200B along the YZ plane of FIG.

  Referring to FIGS. 9 and 10, video display device 1000 </ b> B is different from video display device 1000 in FIG. 2 in that backlight device 200 </ b> B is provided instead of backlight device 200. Since the other configuration of video display apparatus 1000B is the same as that of video display apparatus 1000, detailed description will not be repeated.

  The backlight device 200B is different from the backlight device 200 shown in FIGS. 4 and 5 in that a plurality of diffusion sheets 74A are further provided. Since the other configuration of backlight device 200B is the same as that of backlight device 200, detailed description will not be repeated.

  Specifically, as illustrated in FIGS. 9 and 10, the backlight device 200 </ b> B includes a diffusion sheet 74 </ b> A provided so as to cover the light emitting surface 72 s of each light guide plate 72. That is, in the backlight device 200B, the diffusion sheet 74A is provided on the light emitting surface 72s of each light guide plate 72. The diffusion sheet 74A is a sheet for diffusing light (light L20) applied to the diffusion sheet 74A.

  Hereinafter, the configuration in which the diffusion sheet 74A is provided on the light emitting surface 72s of the light guide plate 72 is also referred to as a modified configuration N1. In the modified configuration N1, the light L20 emitted from the light emitting surface 72s of the light guide plate 72 can be diffused by the diffusion sheet 74A by the action of the diffusion pattern 72a of the light guide plate 72 and the action of the reflection sheet 74. .

  That is, in the configuration in which the distance from the light guide plate 72 to the diffusion plate 75 is short and the luminance distribution of the light irradiated on the display panel 11 varies due to the modified configuration N1, the luminance distribution of the light improves variation. Can do.

  The modified configuration N1 may be applied to the backlight device 200A of the second embodiment.

(Modification A)
In this modification, a modified configuration applicable to the above-described first, second, and third embodiments will be described. The light source 61a in the first, second, and third embodiments is an LED that emits white light, but is not limited thereto. For example, some or all of the plurality of light sources 61a in the first, second, and third embodiments may be configured to be LEDs that emit cyan light (hereinafter also referred to as modified configuration A1).

  The light L10 emitted from the light source 61a in the modified configuration A1 is cyan light. According to the modified configuration A1, the red color reproducibility displayed on the display panel 11 can be improved.

  Further, a part or all of the plurality of light sources 70 in the first, second, and third embodiments may be configured to be a laser that emits red laser light (hereinafter also referred to as modified configuration A2). The range of the wavelength of the light L20 emitted from the light source 70 in the modified configuration A2 is a range from 630 nm to 650 nm. According to the modified configuration A2, the red color reproducibility displayed on the display panel 11 can be improved.

  Moreover, it is good also as a structure (henceforth deformation structure A3) which combined deformation structure A2 with deformation structure A1. In the modified configuration A3, the LED in the modified configuration A1 and the light source 70 in the modified configuration A2 are used.

  In the present invention, within the scope of the invention, each embodiment and the modification of each embodiment can be freely combined, and each embodiment and each modification of the embodiment are appropriately modified and omitted. It is possible.

  For example, in the backlight devices according to Embodiments 1, 2, and 3, the light source 70 is not limited to a semiconductor laser, and may be a light source of another type. The light source 70 may be, for example, an organic EL element or an LED.

  In the backlight devices according to the first, second, and third embodiments, the light source 61a is not limited to the LED, and may be a light source of another method. The light source 61a may be, for example, an organic EL element.

  In the backlight devices according to Embodiments 1, 2, and 3, the light source 70 is provided in association with each of the two incident surfaces of the light guide plate 72. However, the present invention is not limited to this. The light source 70 may be provided in association with only one of the two incident surfaces of the light guide plate 72.

  In the backlight devices according to Embodiments 1, 2, and 3, the lens 61b may not be provided.

  In the backlight devices according to Embodiments 1, 2, and 3, the diffuser plate 75 may not be provided.

  DESCRIPTION OF SYMBOLS 11 Display panel, 12c, 74A Diffusion sheet, 60 Light emission bar, 61 Light source part, 61a, 70 Light source, 72 Light guide plate, 72a Diffusion pattern, 74 Reflection sheet, 75 Diffusion plate, 110 Display part, 200, 200A, 200B, 200N backlight device, 1000, 1000A, 1000B video display device.

Claims (12)

A backlight device that emits light to a display panel that displays images using light,
Equipped with a plurality of elongated light emitting bars,
Each of the plurality of light emitting bars includes a plurality of first light sources arranged in a line,
The plurality of light emitting bars are arranged in parallel to each other, and emit the first light to the display panel,
The backlight device further includes:
A second light source that emits second light;
A light guide plate disposed between the plurality of light emitting bars,
The light guide plate is a backlight device configured to direct the second light emitted from the second light source toward the display panel. The backlight device further includes:
A plurality of light-emitting bars, the second light source, and the light guide plate including a reflective sheet disposed on the main surface.
The backlight device according to claim 1. The light guide plate is provided with a diffusion pattern for diffusing the second light,
The backlight device according to claim 2, wherein the reflection sheet reflects part of the second light so that part of the diffused second light travels toward the display panel. The light guide plate is provided with a plurality of the diffusion patterns,
The backlight device according to claim 3, wherein each of the diffusion patterns is configured such that the longer the distance between the diffusion pattern and the second light source, the larger the size of the diffusion pattern. The light guide plate has a light emitting surface for emitting the second light to the display panel,
The shape of the light emitting surface in plan view is a rectangle,
5. The backlight according to claim 1, wherein the second light source emits the second light to an incident surface that is a side surface of the light guide plate corresponding to a short side of the light emitting surface. apparatus. The backlight device according to claim 5, wherein a plurality of the second light sources that emit the second light to the incident surface are provided. The backlight device further includes:
The backlight device according to claim 5, further comprising a diffusion sheet for diffusing light, which is provided so as to cover the light emitting surface. The backlight device according to claim 1, wherein the second light source is a semiconductor laser. The backlight device according to claim 8, wherein a wavelength range of the second light is a range from 630 nm to 650 nm. The backlight device according to any one of claims 1 to 9, wherein the first light source is an LED (Light Emitting Diode). The backlight device according to claim 10, wherein the first light is cyan light. A video display device including the backlight device according to any one of claims 1 to 11,
An image display device comprising: the display panel that displays the image using the first light and the second light emitted from the backlight device.

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