Display device

Abstract

To provide a display device capable of improving display quality.SOLUTION: According to one embodiment, a display device includes a liquid crystal panel, an illumination device configured to illuminate the liquid crystal panel, and a control unit configured to control the liquid crystal panel and the illumination device. The illumination device includes a first light guide plate having a first side surface, a second light guide plate facing the first light guide plate and having a second side surface, a plurality of first light emitting elements configured to emit light of a first wavelength range toward the first side surface, and a plurality of second light emitting elements configured to emit light of a second wavelength range different from the first wavelength range toward the second side surface. The control unit performs control such that a color image of the first wavelength range is displayed on the liquid crystal panel in synchronization with lighting of the plurality of first light-emitting elements, and a color image of the second wavelength range is displayed on the liquid crystal panel in synchronization with lighting of the plurality of second light-emitting elements.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a display device. [Background technology]

[0002] A field sequential color (FSC) technique is known for displaying images in a display device, in which red, green, and blue light emitting diodes are used as light sources for illuminating a liquid crystal panel.

[0003] However, some of the light-emitting diodes of each color used as such light sources have low light-emitting efficiency relative to the amount of current supplied. When the duty ratio is the lighting time per unit time, light-emitting diodes with low light-emitting efficiency do not provide sufficient brightness when driven at a small duty ratio.

[0004] In particular, in the field sequential color system, the period during which the LEDs of each color can be lit is approximately one-third of one frame period, and it is unavoidable to drive the LEDs of each color at a low duty ratio. For this reason, when LEDs with low luminous efficiency are used, it is necessary to compensate for the decrease in brightness in order to improve display quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-248463 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the embodiment is to provide a display device that can improve display quality. [Means for solving the problem]

[0007] According to an embodiment, the display device comprises: a control unit that controls the liquid crystal panel and the lighting unit, wherein the lighting unit comprises a first light guide plate having a first side surface, a second light guide plate facing the first light guide plate and having a second side surface, a plurality of first light-emitting elements configured to emit light in a first wavelength range toward the first side surface, and a plurality of second light-emitting elements configured to emit light in a second wavelength range different from the first wavelength range toward the second side surface, wherein the number of the plurality of second light-emitting elements is different from the number of the plurality of first light-emitting elements, and the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with the lighting of the plurality of first light-emitting elements, and to display a color image in the second wavelength range in synchronization with the lighting of the plurality of second light-emitting elements.

[0008] According to an embodiment, the display device comprises: a control unit that controls the liquid crystal panel and the lighting device, wherein the lighting device comprises a first light guide plate having a first side surface, a second light guide plate facing the first light guide plate and having a second side surface, a plurality of first light-emitting elements configured to emit light in a first wavelength range toward the first side surface, a plurality of second light-emitting elements configured to emit light in the first wavelength range toward the second side surface, and a wavelength conversion element that converts light in the first wavelength range into light in a second wavelength range different from the first wavelength range, wherein the first light guide plate is located between the second light guide plate and the liquid crystal panel, and the wavelength conversion element is located on an optical path between the plurality of second light-emitting elements and the first light guide plate, and the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with lighting of the plurality of first light-emitting elements, and to display a color image in the second wavelength range in synchronization with lighting of the plurality of second light-emitting elements.

[0009] According to an embodiment, the display device comprises: a plurality of second light-emitting elements configured to emit light in the first wavelength range toward the first side face; a wavelength conversion element located between the plurality of second light-emitting elements and the first side face, the wavelength conversion element converting light in the first wavelength range into light in a second wavelength range different from the first wavelength range; and a plurality of third light-emitting elements configured to emit light in a third wavelength range different from the first wavelength range and the second wavelength range toward the first side face; and the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with lighting of the plurality of first light-emitting elements, to display a color image in the second wavelength range in synchronization with lighting of the plurality of second light-emitting elements, and to display a color image in the third wavelength range in synchronization with lighting of the plurality of third light-emitting elements. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an example of the appearance of a head-mounted display 1. As shown in FIG. [Figure 2] FIG. 2 is a diagram illustrating the configuration of the display device DSP. [Figure 3] FIG. 3 is a plan view for explaining the configuration of the liquid crystal panel PNL. [Figure 4] FIG. 4 is a diagram for explaining the field sequential color method applied to the display device DSP. [Figure 5] FIG. 5 is a diagram showing an example of the configuration of the illumination device IL. [Figure 6] FIG. 6 is a diagram showing another example of the configuration of the illumination device IL. [Figure 7] FIG. 7 is a diagram showing a head-mounted display 1 to which the configuration example shown in FIG. 6 is applied. [Figure 8] FIG. 8 is a diagram showing another example of the configuration of the illumination device IL. [Figure 9] FIG. 9 is a diagram showing another example of the configuration of the illumination device IL. [Figure 10] FIG. 10 is a diagram showing another example of the configuration of the illumination device IL. [Figure 11] FIG. 11 is a diagram showing another example of the configuration of the illumination device IL. [Figure 12] FIG. 12 is a diagram showing another example of the configuration of the illumination device IL. [Figure 13] FIG. 13 is a diagram showing another example of the configuration of the illumination device IL. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily make while maintaining the gist of the disclosure are naturally included within the scope of the present disclosure. Furthermore, in the drawings, the width, thickness, shape, etc. of each part may be schematically depicted compared to the actual embodiment for clarity of explanation, but these are merely examples and are not intended to limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, components that perform the same or similar functions as those described above with respect to the previous drawings are designated by the same reference numerals, and redundant detailed descriptions may be omitted as appropriate.

[0012] In addition, to facilitate understanding, the drawings depict, where necessary, mutually perpendicular X, Y, and Z axes. The direction along the X axis is referred to as the first direction X, the direction along the Y axis is referred to as the second direction Y, and the direction along the Z axis is referred to as the third direction Z. Viewing various elements parallel to the third direction Z is referred to as a planar view. Note that terms referring to the relative positions of two or more components, such as above, above, between, and facing, include not only cases where the two or more components are in direct contact, but also cases where they are separated from each other by a gap or another component.

[0013] FIG. 1 is a perspective view showing an example of the appearance of a head-mounted display 1. As shown in FIG.

[0014] The head mounted display 1 is worn on the head of a user USR, for example. The head mounted display 1 is used to provide the user USR with, for example, virtual reality, augmented reality, or the like.

[0015] The head mounted display 1 includes a display device DSP1 for the left eye and a display device DSP2 for the right eye. The display device DSP1 is disposed so as to be located in front of the left eye of the user USR when the user USR wears the head mounted display 1 on his / her head. The display device DSP2 is disposed so as to be located in front of the right eye of the user USR when the user USR wears the head mounted display 1 on his / her head.

[0016] The display device DSP1 and the display device DSP2 have substantially the same configuration. The following describes a display device DSP that can be applied to each of the display device DSP1 and the display device DSP2.

[0017] FIG. 2 is a diagram illustrating the configuration of the display device DSP.

[0018] The display device DSP includes an illumination device IL, an optical sheet OS, a liquid crystal panel PNL, a projection optical system PO, and a control unit CNT. The control unit CNT is configured to control the illumination device IL and the liquid crystal panel PNL.

[0019] The illumination device IL is disposed behind the liquid crystal panel PNL and configured to illuminate the liquid crystal panel PNL. The illumination device IL includes a plurality of light-emitting elements LD and at least one light guide plate LG. The plurality of light-emitting elements LD include, for example, a plurality of light-emitting elements LD1 configured to emit light in a first wavelength range, a plurality of light-emitting elements LD2 configured to emit light in a second wavelength range, and a plurality of light-emitting elements LD3 configured to emit light in a third wavelength range. The first wavelength range, the second wavelength range, and the third wavelength range are different from each other.

[0020] As an example of the light-emitting element LD, the light-emitting element LD1 is a light-emitting diode configured to emit light in a first wavelength region. The light-emitting element LD2 is a light-emitting diode configured to emit light in a second wavelength region. The light-emitting element LD3 is a light-emitting diode configured to emit light in a third wavelength region. The light-emitting element LD is not limited to a light-emitting diode, and may be a laser diode, which has higher directivity than a light-emitting diode. Furthermore, the light-emitting element LD may be combined with a wavelength conversion element to obtain light in a desired wavelength region.

[0021] These light emitting elements LD are driven by a light source driver DrL, which is controlled by a control unit CNT.

[0022] The liquid crystal panel PNL includes a first substrate SUB1, a second substrate SUB2, a liquid crystal layer LC, and polarizers PL1 and PL2. The liquid crystal layer LC is disposed between the first substrate SUB1 and the second substrate SUB2. The polarizer PL1 is bonded to the first substrate SUB1. The polarizer PL2 is bonded to the second substrate SUB2.

[0023] Such a liquid crystal panel PNL is driven by a panel driver DrP, which is controlled by a control unit CNT.

[0024] The optical sheets OS are arranged between the illumination device IL and the liquid crystal panel PNL. The optical sheets OS are, for example, prism sheets or diffusion sheets.

[0025] The projection optical system PO is disposed between the user's observation position O and the liquid crystal panel PNL, and is configured to project an image displayed on the liquid crystal panel PNL toward the user's eye E. The projection optical system PO is composed of various optical elements. For example, the projection optical system PO is an optical system known as a pancake optical system, which has at least two reflecting surfaces and has the function of folding the optical path twice.

[0026] FIG. 3 is a plan view for explaining the configuration of the liquid crystal panel PNL.

[0027] In a plan view, the first substrate SUB1 and the second substrate SUB2 overlap each other and are bonded to each other by a seal SE. The liquid crystal layer LC is sealed between the first substrate SUB1 and the second substrate SUB2 by the seal SE.

[0028] The liquid crystal panel PNL has a display area DA for displaying an image in an area where the liquid crystal layer LC is sealed. The display area DA has a plurality of pixels PX arranged in a matrix in a first direction X and a second direction Y. A plurality of scanning lines GL each extend in the first direction X and are aligned in the second direction Y. A plurality of signal lines SL each extend in the second direction Y and are aligned in the first direction X.

[0029] In the illustrated example, an IC chip CP and a flexible printed circuit board FP for driving the liquid crystal panel PNL are mounted on a first substrate SUB1. The IC chip CP may also be mounted on the flexible printed circuit board FP. The panel driver DrP shown in FIG. 2 includes a signal line driver that applies a voltage to each signal line SL according to a video signal, and a scanning line driver that applies a voltage to each scanning line GL according to a control signal. Such a panel driver DrP is, for example, built into the IC chip CP.

[0030] In the example shown in FIG. 3, the first substrate SUB1 and the second substrate SUB2 each have a rectangular shape in a plan view, but this is not limited to this and they may be polygonal shapes other than rectangular, or may be circular or elliptical.

[0031] FIG. 4 is a diagram for explaining the field sequential color method applied to the display device DSP.

[0032] The horizontal axis in the figure represents time. One frame period F for displaying a color image in the display area DA of the liquid crystal panel PNL has a sub-frame period SF1 for displaying a color image in the first wavelength range, a sub-frame period SF2 for displaying a color image in the second wavelength range, and a sub-frame period SF3 for displaying a color image in the third wavelength range.

[0033] The sub-frame period SF1 includes a period T11 during which video signals corresponding to a color image in the first wavelength range are written to all pixels PX of the liquid crystal panel PNL, and a period T12 during which the video signals written to the pixels PX are held. During the period T12, the light-emitting elements LD1 can be turned on at a predetermined duty ratio.

[0034] The sub-frame period SF2 includes a period T21 during which video signals corresponding to a color image in the second wavelength range are written to all pixels PX of the liquid crystal panel PNL, and a period T22 during which the video signals written to the pixels PX are held. During the period T22, the light-emitting elements LD2 can be turned on at a predetermined duty ratio.

[0035] The sub-frame period SF3 includes a period T31 during which video signals corresponding to a color image in the third wavelength range are written to all pixels PX of the liquid crystal panel PNL, and a period T32 during which the video signals written to the pixels PX are held. During the period T32, the light-emitting elements LD3 are turned on at a predetermined duty ratio.

[0036] The control unit CNT shown in Figure 2 controls the light source driver DrL and the panel driver DrP, and first controls the liquid crystal panel PNL to display a color image in a first wavelength range in synchronization with the lighting of multiple light-emitting elements LD1 during sub-frame period SF1. Then, the control unit CNT controls the liquid crystal panel PNL to display a color image in a second wavelength range in synchronization with the lighting of multiple light-emitting elements LD2 during sub-frame period SF2. Then, the control unit CNT controls the liquid crystal panel PNL to display a color image in a third wavelength range in synchronization with the lighting of multiple light-emitting elements LD3 during sub-frame period SF3. This allows a color image to be provided to the user.

[0037] Next, several configuration examples of the illumination device IL will be described. In the following description, the third direction Z corresponds to the thickness direction of the illumination device IL, and the plane defined by the first direction X and the second direction Y will be referred to as the XY plane, the plane defined by the first direction X and the third direction Z will be referred to as the XZ plane, and the plane defined by the second direction Y and the third direction Z will be referred to as the YZ plane. In each configuration example, the same components will be given the same reference symbols, and duplicate descriptions may be omitted as appropriate.

[0038] FIG. 5 is a diagram showing an example of the configuration of the illumination device IL.

[0039] The illumination device IL includes a light guide plate LG1, a light guide plate LG2, a plurality of light emitting elements LD1, a plurality of light emitting elements LD2, and a plurality of light emitting elements LD3. The light guide plates LG1 and LG2 are formed in the shape of flat plates having main surfaces along the XY plane.

[0040] The light guide plate LG2 faces the light guide plate LG1 in the third direction Z. The light guide plate LG1 is located between the liquid crystal panel PNL and the light guide plate LG2. No optical member is interposed between the light guide plate LG1 and the light guide plate LG2. The main surfaces of the light guide plate LG1 and the light guide plate LG2 face each other with an air layer between them.

[0041] The light guide plate LG1 has a side surface S1. The side surface S1 has a portion S11 along the first direction X, a portion S12 along the second direction Y, a portion S13 along the first direction X, and a portion S14 along the second direction Y. The portions S11 and S13 are surfaces parallel to the XZ plane. The portions S12 and S14 are surfaces parallel to the YZ plane.

[0042] The light guide plate LG2 has a side surface S2. The side surface S2 has a portion S21 along the first direction X, a portion S22 along the second direction Y, a portion S23 along the first direction X, and a portion S24 along the second direction Y. The portions S21 and S23 are surfaces parallel to the XZ plane. The portions S22 and S24 are surfaces parallel to the YZ plane.

[0043] When the light guide plates LG1 and LG2 are formed to have the same dimensions, in the third direction Z, the portions S11 and S21 overlap each other, the portions S12 and S22 overlap each other, the portions S13 and S23 overlap each other, and the portions S14 and S24 overlap each other.

[0044] The plurality of light-emitting elements LD1 and the plurality of light-emitting elements LD3 face the side surface S1. In the illustrated example, the plurality of light-emitting elements LD1 and the plurality of light-emitting elements LD3 face the portion S11 of the side surface S1 in the second direction Y and are arranged alternately in the first direction X.

[0045] The plurality of light-emitting elements LD2 face the side surface S2. In the illustrated example, the plurality of light-emitting elements LD2 face the portion S21 of the side surface S2 in the second direction Y and are lined up in the first direction X. The number of the plurality of light-emitting elements LD2 is different from the number of the plurality of light-emitting elements LD1 and different from the number of the plurality of light-emitting elements LD3. In the illustrated example, the number of the plurality of light-emitting elements LD2 is greater than the number of the plurality of light-emitting elements LD1 and is greater than the number of the plurality of light-emitting elements LD3.

[0046] 5, a plurality of light-emitting elements LD1 and a plurality of light-emitting elements LD3 face only one portion S11 of the side surface S1, and no light-emitting elements are provided facing the other three portions S12, S13, and S14. Similarly, a plurality of light-emitting elements LD2 face only one portion S21 of the side surface S2, and no light-emitting elements are provided facing the other three portions S22, S23, and S24.

[0047] The light-emitting elements LD1 and LD3 are provided at positions overlapping the light-emitting elements LD2, but this is not limiting. For example, the light-emitting elements LD1 and LD3 may face the portion S11, and the light-emitting elements LD2 may face any one of the portions S22, S23, and S24.

[0048] In this lighting device IL, light emitted from the plurality of light-emitting elements LD1 propagates through the light guide plate LG1 and forms illumination light in a first wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD2 propagates through the light guide plate LG2 and, after passing through the light guide plate LG1, forms illumination light in a second wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD3 propagates through the light guide plate LG1 and forms illumination light in a third wavelength range for illuminating the liquid crystal panel PNL.

[0049] Here, it is assumed that the light-emitting element LD2 has a lower light-emitting efficiency than the other light-emitting elements LD1 and LD3. According to the illustrated configuration example, the number of light-emitting elements LD2 can be greater than the number of light-emitting elements LD1, and can also be greater than the number of light-emitting elements LD3. Therefore, even when the number of light-emitting elements LD2 is driven at a small duty ratio, sufficient brightness can be obtained.

[0050] Therefore, according to the above configuration example, when a color image is displayed using the field sequential color method, a good white balance can be obtained and the display quality can be improved compared to when the numbers of light-emitting elements LD1, light-emitting elements LD2, and light-emitting elements LD3 are the same.

[0051] FIG. 6 is a diagram showing another example of the configuration of the illumination device IL.

[0052] The configuration example shown in Fig. 6 differs from the configuration example shown in Fig. 5 in that the plurality of light-emitting elements LD1 face two portions S11 and S12 of the side surface S1, the plurality of light-emitting elements LD2 face two portions S21 and S22 of the side surface S2, and the plurality of light-emitting elements LD3 face two portions S11 and S12 of the side surface S1. Although not shown, the plurality of light-emitting elements LD1 and the plurality of light-emitting elements LD3 may face three or more portions of the side surface S1. Furthermore, the plurality of light-emitting elements LD2 may face three or more portions of the side surface S2.

[0053] In this configuration example, the same effects as those described with reference to Fig. 5 can be obtained. In addition, a larger number of light-emitting elements can be installed, and higher brightness can be obtained.

[0054] FIG. 7 is a diagram showing a head-mounted display 1 to which the configuration example shown in FIG. 6 is applied.

[0055] In each of the display devices DSP1 and DSP2, the liquid crystal panel PNL is formed in an octagonal shape. Also, each of the light guide plates LG1 and LG2 of the illumination device IL has a notch LGC to avoid contact with the user's nose NS.

[0056] 6 are not provided in the cutout LGC or in the vicinity of the cutout LGC. That is, the light emitting elements LD are not provided facing the portions S13 and S14 of the light guide plate LG1 that are adjacent to the cutout LGC. Furthermore, the light emitting elements LD are not provided facing the portions S23 and S24 of the light guide plate LG2 that are adjacent to the cutout LGC.

[0057] In the configuration examples described above with reference to Figures 5 to 7, the second wavelength range is longer than the first wavelength range, and the third wavelength range is longer than the second wavelength range. More specifically, the first wavelength range is 400 nm to 500 nm, and the color of the first wavelength range is blue. The second wavelength range is 500 nm to 600 nm, and the color of the second wavelength range is green. The third wavelength range is 600 nm to 700 nm, and the color of the third wavelength range is red. That is, the light-emitting element LD1 shown in Figures 5 and 6 corresponds to the first light-emitting element configured to emit blue light, the light-emitting element LD2 corresponds to the second light-emitting element configured to emit green light, and the light-emitting element LD3 corresponds to the third light-emitting element configured to emit red light.

[0058] However, the first wavelength range, the second wavelength range, and the third wavelength range are not limited to the above examples. For example, the third wavelength range may have a longer wavelength than the first wavelength range, and the second wavelength range may have a longer wavelength than the third wavelength range. That is, the color of the second wavelength range may be red, and the color of the third wavelength range may be green. In this case, the light-emitting element LD2 shown in FIGS. 5 and 6 is configured to emit red light, and the light-emitting element LD3 is configured to emit green light.

[0059] FIG. 8 is a diagram showing another example of the configuration of the illumination device IL.

[0060] The lighting device IL includes a light guide plate LG1, a light guide plate LG2, a light guide plate LG3, a plurality of light emitting elements LD1, a plurality of light emitting elements LD2, and a plurality of light emitting elements LD3.

[0061] The light guide plate LG2 faces the light guide plate LG1 in the third direction Z. The light guide plate LG1 is located between the liquid crystal panel PNL and the light guide plate LG2. The light guide plate LG3 faces the light guide plate LG2 in the third direction Z. The light guide plate LG2 is located between the light guide plate LG1 and the light guide plate LG3. No optical member is interposed between the light guide plate LG1 and the light guide plate LG2, and between the light guide plate LG2 and the light guide plate LG3.

[0062] As described above, the light guide plate LG1 has a side surface S1 that includes the portion S11. As described above, the light guide plate LG2 has a side surface S2 that includes the portion S21.

[0063] The light guide plate LG3 has a side surface S3. The side surface S3 includes a portion S31 along the first direction X. The portion S31 is a surface parallel to the XZ plane.

[0064] The light emitting elements LD1 face the side surface S1. In the illustrated example, the light emitting elements LD1 face the portion S11 of the side surface S1 in the second direction Y and are aligned in the first direction X. The light emitting elements LD2 face the side surface S2. In the illustrated example, the light emitting elements LD2 face the portion S21 of the side surface S2 in the second direction Y and are aligned in the first direction X. The plurality of light-emitting elements LD3 face the side surface S3. In the illustrated example, the plurality of light-emitting elements LD3 face the portion S31 of the side surface S3 in the second direction Y and are aligned in the first direction X.

[0065] In this lighting device IL, light emitted from the plurality of light-emitting elements LD1 propagates through the light guide plate LG1 and forms illumination light in a first wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD2 propagates through the light guide plate LG2 and, after passing through the light guide plate LG1, forms illumination light in a second wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD3 propagates through the light guide plate LG3 and, after passing through the light guide plate LG2 and the light guide plate LG1 in this order, forms illumination light in a third wavelength range for illuminating the liquid crystal panel PNL.

[0066] In this configuration example as well, the same effects as those of the configuration example described with reference to FIG. 5 can be obtained.

[0067] 8, the light emitting element LD3, which is farthest from the liquid crystal panel PNL, desirably has higher luminous efficiency (or higher luminance) than the other light emitting elements LD1 and LD2 because the emitted light reaches the liquid crystal panel PNL via three light guide plates. Conversely, the light emitting element LD1, which is closest to the liquid crystal panel PNL, desirably has lower luminous efficiency (or lower luminance) than the other light emitting elements LD2 and LD3.

[0068] In one example, the light-emitting element LD1 is configured to emit red or green light, and the light-emitting element LD3 is configured to emit blue light.

[0069] Furthermore, the numbers of the light-emitting elements LD1, LD2, and LD3 may be the same or different. When the light-emitting efficiency of the light-emitting element LD1 is lower than the light-emitting efficiency of the other light-emitting elements LD2 and LD3, it is desirable that the number of the plurality of light-emitting elements LD1 is greater than the number of the plurality of light-emitting elements LD2 and greater than the number of the plurality of light-emitting elements LD3.

[0070] FIG. 9 is a diagram showing another example of the configuration of the illumination device IL.

[0071] The lighting device IL includes a light guide plate LG1, a light guide plate LG2, a plurality of light emitting elements LD1, a plurality of light emitting elements LD2, a plurality of light emitting elements LD3, and a wavelength conversion element WC.

[0072] The plurality of light-emitting elements LD1 are configured to emit light in a first wavelength range toward the light guide plate LG1. The plurality of light-emitting elements LD2 are configured to emit light in the first wavelength range toward the light guide plate LG2. The light-emitting elements LD2 are identical to the light-emitting elements LD1. The plurality of light-emitting elements LD3 are configured to emit light in a third wavelength range different from the first wavelength range toward the light guide plate LG1.

[0073] The number of the plurality of light-emitting elements LD1, the number of the plurality of light-emitting elements LD2, and the number of the plurality of light-emitting elements LD3 may be the same or different from each other.

[0074] The plurality of light emitting elements LD1 and the plurality of light emitting elements LD3 face the portion S11 of the side surface S1 in the second direction Y and are arranged alternately in the first direction X. The plurality of light emitting elements LD2 face the portion S21 of the side surface S2 and are arranged in the first direction X.

[0075] The light guide plate LG1 is located between the liquid crystal panel PNL and the light guide plate LG2.

[0076] The wavelength conversion element WC has a function of converting light in, for example, a first wavelength region into light in a second wavelength region. In other words, the color of light incident on the wavelength conversion element WC is different from the color of light transmitted through the wavelength conversion element WC. Such a wavelength conversion element WC is located on the optical path between the plurality of light emitting elements LD2 and the light guide plate LG1. In the illustrated example, the wavelength conversion element WC is located between the light guide plate LG1 and the light guide plate LG2.

[0077] In this lighting device IL, light emitted from the plurality of light-emitting elements LD1 propagates through the light guide plate LG1 and forms illumination light in a first wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD2 propagates through the light guide plate LG2 and is converted into light in a second wavelength range when passing through the wavelength conversion element WC, and after passing through the light guide plate LG1, forms illumination light in the second wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the plurality of light-emitting elements LD3 propagates through the light guide plate LG1 and forms illumination light in a third wavelength range for illuminating the liquid crystal panel PNL.

[0078] 9, a light emitting element having a relatively high luminous efficiency equivalent to the light emitting element LD1 is used as the light emitting element LD2, and by combining the light emitting element LD2 with the wavelength conversion element WC, illumination light in the second wavelength range can be generated. In other words, a light emitting element having a low luminous efficiency is not used, and instead, a combination of a light emitting element having a high luminous efficiency and a wavelength conversion element is used.

[0079] This makes it possible to obtain a good white balance when displaying a color image using the field sequential color system, thereby improving the display quality.

[0080] FIG. 10 is a diagram showing another example of the configuration of the illumination device IL.

[0081] The configuration example shown in FIG. 10 differs from the configuration example shown in FIG. 9 in that the lighting device IL further includes a color filter CF. The color filter CF is colored in a color of a second wavelength range. When the color of the second wavelength range is green, the color filter CF is a green color filter. Focusing on the transmittance characteristics of the color filter CF, it is desirable that the transmittance in the second wavelength range is higher than the transmittance in the first wavelength range, and furthermore, the transmittance in the first wavelength range is extremely low. Furthermore, the central wavelength of the light emitted from the light emitting element LD2 is included in the first wavelength range and is sufficiently absorbed by the color filter CF.

[0082] The wavelength conversion element WC and the color filter CF are both located between the light guide plate LG1 and the light guide plate LG2. The color filter CF is located between the wavelength conversion element WC and the light guide plate LG1.

[0083] 10, of the light in the first wavelength range emitted from the light-emitting element LD2, the light that passes through the wavelength conversion element WC is absorbed by the color filter CF. Furthermore, of the light in the first wavelength range emitted from the light-emitting element LD2, the light that is converted to the second wavelength range by the wavelength conversion element WC passes through the color filter CF. Therefore, illumination light in the second wavelength range with high color purity can be formed.

[0084] FIG. 11 is a diagram showing another example of the configuration of the illumination device IL.

[0085] The configuration example shown in FIG. 11 differs from the configuration example shown in FIG. 9 in that the wavelength conversion element WC is located between the plurality of light emitting elements LD2 and the side surface S2 of the light guide plate LG2.

[0086] In such an illumination device IL, the light emitted from the multiple light-emitting elements LD2 is converted into light in the second wavelength range when passing through the wavelength conversion element WC, propagates through the light guide plate LG2, and after passing through the light guide plate LG1, forms illumination light in the second wavelength range for illuminating the liquid crystal panel PNL.

[0087] The configuration example shown in FIG. 11 also provides the same effects as the configuration example shown in FIG.

[0088] FIG. 12 is a diagram showing another example of the configuration of the illumination device IL.

[0089] The configuration example shown in Fig. 12 differs from the configuration example shown in Fig. 11 in that the illumination device IL further includes a color filter CF. The color filter CF is colored in a color in the second wavelength range and is located between the light guide plates LG1 and LG2.

[0090] The configuration example shown in FIG. 12 also provides the same effects as the configuration example shown in FIG.

[0091] FIG. 13 is a diagram showing another example of the configuration of the illumination device IL.

[0092] The lighting device IL includes a light guide plate LG1, a plurality of light emitting elements LD1, a plurality of light emitting elements LD2, a plurality of light emitting elements LD3, and a wavelength conversion element WC.

[0093] The plurality of light-emitting elements LD1 are configured to emit light in a first wavelength range toward the light guide plate LG1. The plurality of light-emitting elements LD2 are configured to emit light in the first wavelength range toward the light guide plate LG1. The light-emitting elements LD2 are identical to the light-emitting element LD1. The plurality of light-emitting elements LD3 are configured to emit light in a third wavelength range different from the first wavelength range toward the light guide plate LG1.

[0094] The plurality of light-emitting elements LD1, the plurality of light-emitting elements LD2, and the plurality of light-emitting elements LD3 face the portion S11 of the side surface S1 in the second direction Y. One of the plurality of light-emitting elements LD1, one of the plurality of light-emitting elements LD2, and one of the plurality of light-emitting elements LD3 are lined up in order in the first direction X. The wavelength conversion element WC has a function of converting, for example, light in a first wavelength region into light in a second wavelength region. The wavelength conversion element WC is located between the plurality of light emitting elements LD2 and the side surface S1 of the light guide plate LG2.

[0095] In this lighting device IL, light emitted from the multiple light-emitting elements LD1 propagates through the light guide plate LG1 to form illumination light in a first wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the multiple light-emitting elements LD2 is converted to light in a second wavelength range when passing through the wavelength conversion element WC, propagates through the light guide plate LG1, and forms illumination light in the second wavelength range for illuminating the liquid crystal panel PNL. Light emitted from the multiple light-emitting elements LD3 propagates through the light guide plate LG1 to form illumination light in a third wavelength range for illuminating the liquid crystal panel PNL.

[0096] The configuration example shown in FIG. 13 also provides the same effects as the configuration example shown in FIG.

[0097] In the above embodiment, for example, light emitting element LD1 corresponds to the first light emitting element, light emitting element LD2 corresponds to the second light emitting element, and light emitting element LD3 corresponds to the third light emitting element. Furthermore, light guide plate LG1 corresponds to the first light guide plate, side surface S1 corresponds to the first side surface, portion S11 corresponds to the first portion, and portion S12 corresponds to the second portion. Furthermore, light guide plate LG2 corresponds to the second light guide plate, side surface S2 corresponds to the second side surface, portion S21 corresponds to the third portion, and portion S22 corresponds to the fourth portion.

[0098] According to the embodiment described above, it is possible to provide a display device capable of improving display quality.

[0099] Although several embodiments of the present disclosure have been described, these embodiments are presented as examples and are not intended to limit the scope of the disclosure. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the disclosure. These embodiments and their modifications are included within the scope and spirit of the disclosure, as well as within the scope of the disclosure and its equivalents as set forth in the claims. [Explanation of symbols]

[0100] DSP: Display device PNL: Liquid crystal panel IL: Lighting device CNT: Control unit LG1, LG2...Light guide plate S1, S2...Side LD1, LD2, LD3...light emitting elements WC: Wavelength conversion element CF: Color filter

Claims

1. An LCD panel, an illumination device configured to illuminate the liquid crystal panel; a control unit that controls the liquid crystal panel and the lighting device, The lighting device includes: a first light guide plate having a first side surface; a second light guide plate facing the first light guide plate and having a second side surface; a plurality of first light-emitting elements configured to emit light in a first wavelength range toward the first side surface; a plurality of second light-emitting elements configured to emit light in a second wavelength range different from the first wavelength range toward the second side surface, The number of the second light-emitting elements is different from the number of the first light-emitting elements, the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with lighting of the plurality of first light-emitting elements, and to display a color image in the second wavelength range in synchronization with lighting of the plurality of second light-emitting elements. Display device.

2. The lighting device further comprises: a plurality of third light-emitting elements configured to emit light in a third wavelength range different from the first wavelength range and the second wavelength range toward the first side surface, The plurality of first light-emitting elements and the plurality of third light-emitting elements are arranged alternately. The display device according to claim 1 .

3. the second wavelength range is longer than the first wavelength range, The third wavelength range is longer than the second wavelength range. The display device according to claim 2 .

4. The number of the second light-emitting elements is greater than the number of the first light-emitting elements and greater than the number of the third light-emitting elements. The display device according to claim 2 .

5. In the first light guide plate, the first side surface has a first portion extending in a first direction and a second portion extending in a second direction different from the first direction, In the second light guide plate, the second side surface has a third portion extending in the first direction and a fourth portion extending in the second direction, the plurality of first light-emitting elements and the plurality of third light-emitting elements face the first portion and the second portion, the plurality of second light-emitting elements face the third portion and the fourth portion; The display device according to claim 2 .

6. The lighting device further comprises: a third light guide plate facing the second light guide plate and having a third side surface; a plurality of third light-emitting elements configured to emit light in a third wavelength range different from the first wavelength range and the second wavelength range toward the third side surface, The display device according to claim 1 .

7. An LCD panel, an illumination device configured to illuminate the liquid crystal panel; a control unit that controls the liquid crystal panel and the lighting device, The lighting device includes: a first light guide plate having a first side surface; a second light guide plate facing the first light guide plate and having a second side surface; a plurality of first light-emitting elements configured to emit light in a first wavelength range toward the first side surface; a plurality of second light-emitting elements configured to emit light in the first wavelength range toward the second side surface; a wavelength conversion element that converts light in the first wavelength range into light in a second wavelength range different from the first wavelength range, the first light guide plate is located between the second light guide plate and the liquid crystal panel; the wavelength conversion element is located on an optical path between the plurality of second light-emitting elements and the first light guide plate, the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with lighting of the plurality of first light-emitting elements, and to display a color image in the second wavelength range in synchronization with lighting of the plurality of second light-emitting elements. Display device.

8. The wavelength conversion element is located between the first light guide plate and the second light guide plate. The display device according to claim 7 .

9. The lighting device further comprises: a color filter located between the wavelength conversion element and the first light guide plate and colored in the second wavelength range; The display device according to claim 8 .

10. the wavelength conversion element is located between the plurality of second light-emitting elements and the second side surface of the second light guide plate; The display device according to claim 7 .

11. The lighting device further comprises: a color filter located between the first light guide plate and the second light guide plate and colored in the second wavelength range; The display device according to claim 10.

12. An LCD panel, an illumination device configured to illuminate the liquid crystal panel; a control unit that controls the liquid crystal panel and the lighting device, The lighting device includes: a first light guide plate having a first side surface; a plurality of first light-emitting elements configured to emit light in a first wavelength range toward the first side surface; a plurality of second light-emitting elements configured to emit light in the first wavelength range toward the first side surface; a wavelength conversion element located between the plurality of second light-emitting elements and the first side surface, the wavelength conversion element converting light in the first wavelength range into light in a second wavelength range different from the first wavelength range; a plurality of third light-emitting elements configured to emit light in a third wavelength range different from the first wavelength range and the second wavelength range toward the first side surface, the control unit controls the liquid crystal panel to display a color image in the first wavelength range in synchronization with lighting of the plurality of first light-emitting elements, controls the liquid crystal panel to display a color image in the second wavelength range in synchronization with lighting of the plurality of second light-emitting elements, and controls the liquid crystal panel to display a color image in the third wavelength range in synchronization with lighting of the plurality of third light-emitting elements. Display device.

Images