Display device and control method

Abstract

To provide a display device capable of improving display quality. [Solution] A display device according to one embodiment includes a display panel for displaying an image, a light guide plate having sides and facing the display panel, a light source unit facing the sides and irradiating the light guide plate with light, and a controller for controlling the light source unit. The light source unit has a plurality of first light-emitting elements that emit light of the same color and are arranged along the sides. The controller controls two adjacent first light-emitting elements so that the illumination time per cycle of one first light-emitting element that is further away from the center of the side is shorter than the illumination time per cycle of the other first light-emitting element, when the period from when the light source unit is turned on until it is turned on again is defined as one cycle.

Description

Technical Field

[0001] Embodiments of the present invention relate to a display device and a control method.

Background Art

[0002] For example, a display device such as a liquid crystal display device includes a display panel having pixels and a lighting device such as a backlight that illuminates the display panel. The lighting device includes a light source and a light guide plate that emits light from this light source. The light from the light source enters the light guide plate, propagates through the light guide plate, and exits from the exit surface of the light guide plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] One object of the present invention is to provide a display device and a control method capable of improving display quality.

Means for Solving the Problems

[0005] A display device according to one embodiment includes a display panel for displaying an image, a light guide plate having sides and facing the display panel, a light source unit facing the sides and irradiating the light guide plate with light, and a controller for controlling the light source unit. The light source unit has a plurality of first light-emitting elements that emit light of the same color and are arranged along the sides. The controller controls two adjacent first light-emitting elements so that the illumination time per cycle of one first light-emitting element that is further away from the center of the side is shorter than the illumination time per cycle of the other first light-emitting element, when the period from when the light source unit is turned on until it is turned on again is defined as one cycle.

[0006] A control method for a display device according to one embodiment includes, when the period from when the light source unit is turned on until it is turned on again is defined as one cycle, the lighting time per cycle of one of two adjacent light-emitting elements of the same color that are located further apart from the center of the side surface of the light source unit is made shorter than the lighting time per cycle of the other light-emitting element. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is an exploded perspective view showing an example configuration of a display device according to one embodiment. [Figure 2] Figure 2 is a block diagram showing an example configuration of a display device according to one embodiment. [Figure 3] Figure 3 is a schematic plan view of the lighting device shown in Figure 1. [Figure 4] Figure 4 is a schematic cross-sectional view of the display device shown in Figure 1. [Figure 5] Figure 5 is a schematic plan view of the light guide plate and light source unit shown in Figure 3. [Figure 6] Figure 6 is a timing chart showing an example of control of a light-emitting element by a controller. [Figure 7] Figure 7 is a timing chart showing an example of control of a light-emitting element by a controller. [Figure 8] Figure 8 is a timing chart showing an example of control of a light-emitting element by a controller. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings. It should be noted that the disclosure is merely an example, and any modifications that a person skilled in the art could easily conceive while maintaining the spirit of the invention are naturally included within the scope of the present invention.

[0009] Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, the same reference numerals are used for components that perform the same or similar functions as those described above with respect to previously shown drawings, and redundant detailed explanations may be omitted as appropriate.

[0010] Furthermore, the drawings will include mutually orthogonal X, Y, and Z axes as needed to facilitate understanding. The direction along the X axis will be referred to as the first direction X, the direction along the Y axis as the second direction Y, and the direction along the Z axis as the third direction Z. In this specification, the third direction Z may be referred to as "upwards" or "up," and the direction opposite to the third direction Z may be referred to as "downwards" or "down."

[0011] In this embodiment, a liquid crystal display device is disclosed as an example of a display device. However, the technical concept disclosed in this embodiment is applicable to other display devices, such as those equipped with other types of display elements, such as organic electroluminescent display elements, micro-LEDs, or mini-LEDs. Furthermore, the technical concept disclosed in this embodiment is also applicable to array substrates and electronic devices having sensor elements such as capacitive sensors and optical sensors.

[0012] The display device according to the present embodiment can be used in various devices such as in-vehicle devices, smartphones, tablet terminals, mobile phone terminals, personal computers, television receivers, game devices, head-mounted displays (e.g., for VR), etc.

[0013] FIG. 1 is an exploded perspective view showing a configuration example of a display device DSP according to the present embodiment. The display device DSP includes a display panel PNL, a lighting device IL, an IC chip No. 1, and a wiring board No. 2.

[0014] The display panel PNL includes a first substrate SUB1, a second substrate SUB2, and a liquid crystal layer LC. The first substrate SUB1 and the second substrate SUB2 face each other. The liquid crystal layer LC is disposed between the first substrate SUB1 and the second substrate SUB2.

[0015] The display panel PNL has a display area DA for displaying an image and a frame-shaped peripheral area SA surrounding the display area DA. The display area DA is located substantially at the center of the area where the first substrate SUB1 and the second substrate SUB2 face each other. The display panel PNL has a plurality of pixels PX arranged in a matrix in the first direction X and the second direction Y in the display area DA. [[ID=1,4]]

[0016] In the example shown in FIG. 1, the first substrate SUB1 has a mounting area MT formed in a portion protruding in a direction opposite to the second direction Y from the second substrate SUB2. The mounting area MT is a part of the peripheral area SA.

[0017] The IC chip No. 1 and the wiring board No. 2 are mounted in the mounting area MT. The IC chip No. 1 and the wiring board No. 2 mainly function as signal sources for supplying control signals to the display panel PNL. The wiring board No. 2 is, for example, a flexible printed board that can be bent. Note that the IC chip No. 1 may be provided on the wiring board No. 2.

[0018] The lighting device IL illuminates the display panel PNL. The lighting device IL includes light guide plates LG1 and LG2, and light source units LU1 and LU2. The light guide plate LG2, the light guide plate LG1, the first substrate SUB1, and the second substrate SUB2 are laminated in this order in the third direction Z.

[0019] The light guide plates LG1 and LG2 are insulating substrates such as glass substrates and plastic substrates. The light guide plate LG2 may be formed of the same material as the light guide plate LG1, or may not be formed of the same material as the light guide plate LG1.

[0020] The light guide plates LG1 and LG2 are formed in a flat plate shape parallel to the X-Y plane defined by the first direction X and the second direction Y. The sizes of the light guide plates LG1 and LG2 are, for example, equal to each other.

[0021] The light guide plate LG1 has a main surface 1A facing the display panel PNL, a main surface 1B on the opposite side of the main surface 1A, and side surfaces SF1 and SF2 connecting the main surfaces 1A and 1B. The side surfaces SF1 and SF2 extend in the first direction X. The side surface SF1 faces the direction opposite to the second direction Y, and the side surface SF2 faces the second direction Y.

[0022] The light guide plate LG2 has a main surface 2A facing the main surface 1B, a main surface 2B on the opposite side of the main surface 2A, and side surfaces SF3 and SF4 connecting the main surfaces 2A and 2B. The main surface 2A faces the display panel PNL through the light guide plate LG1. The side surfaces SF3 and SF4 extend in the first direction X. The side surface SF3 faces the direction opposite to the second direction Y, and the side surface SF4 faces the second direction Y.

[0023] The light source unit LU1 irradiates light toward the side surface SF2. In other words, the light emission direction of the light source unit LU1 is the direction opposite to the second direction Y. The light source unit LU1 faces the side surface SF2.

[0024] Light source unit LU2 emits light toward side SF3. In other words, the direction of light emission from light source unit LU2 is the second direction Y. The direction of light emission from light source unit LU2 is opposite to the direction of light emission from light source unit LU1. Light source unit LU2 faces side SF3.

[0025] Figure 2 is a block diagram showing an example configuration of a display device DSP according to this embodiment. The display device DSP further includes a controller CNT. The controller CNT controls the display panel PNL and the light source units LU1 and LU2, respectively. The controller CNT controls the display panel PNL via, for example, an IC chip 1 (shown in Figure 1).

[0026] Furthermore, the controller CNT controls the light source by supplying light source control signals to the light source units LU1 and LU2, respectively, in sync with supplying control signals to the display panel PNL. As a result, an image is displayed in the display area DA. Here, an image can be, for example, text, photographs, illustrations, or videos.

[0027] Figure 3 is a schematic plan view of the lighting device IL shown in Figure 1. In Figure 3, the lighting device IL is viewed in the direction opposite to the third direction Z. The light guide plates LG1 and LG2 have a long rectangular shape in the second direction Y.

[0028] The lighting device IL has a first region A1 and a second region A2. The first region A1 and the second region A2 are aligned in this order in the second direction Y. Sides SF1 and SF3 are located in the first region A1, and sides SF2 and SF4 are located in the second region A2.

[0029] Here, the boundary between the first region A1 and the second region A2 is defined as boundary BO, and the line passing through the center of the width in the first direction X on the light guide plates LG1 and LG2 is defined as center line XCT. The region including the intersection of the sides SF2 and SF3 and center line XCT is sometimes referred to as the center of sides SF2 and SF3. The size of the first region A1 is, for example, equal to the size of the second region A2. In other words, boundary BO passes through the center of the width in the second direction Y on the light guide plates LG1 and LG2.

[0030] Light source units LU1 and LU2 each have multiple light-emitting elements that emit light of different colors. These multiple light-emitting elements include multiple red light-emitting elements (LDR), multiple green light-emitting elements (LDG), and multiple blue light-emitting elements (LDB). In other words, the LDR, LDG, and LDB elements each emit light of the same color.

[0031] The light-emitting elements LDR, LDG, and LDB are, for example, laser light sources (e.g., laser diodes) that emit polarized laser light. In this embodiment, the light-emitting element LDR is an example of a first light-emitting element, the light-emitting element LDG is an example of a third light-emitting element, and the light-emitting element LDB is an example of a second light-emitting element.

[0032] For example, the light-emitting elements LDR, LDG, and LDB are arranged in this order, repeating at intervals in the first direction X. In other words, the light-emitting elements LDR, LDG, and LDB are arranged in this order along the sides SF2 and SF3. The intervals are, for example, equal, but are not limited to this example.

[0033] The light source units LU1 and LU2 can obtain mixed-color light (e.g., white) by adjusting the light emitted by the light-emitting elements LDR, LDG, and LDB, for example, through additive color mixing. The light source units LU1 and LU2 may further include light-emitting elements that emit colors other than red, green, and blue.

[0034] Figure 4 is a schematic cross-sectional view of the display device DSP shown in Figure 1. The display panel PNL further comprises a seal SE and polarizing plates PL1 and PL2.

[0035] The seal SE is located between the first substrate SUB1 and the second substrate SUB2. The seal SE adheres the first substrate SUB1 and the second substrate SUB2 together. Furthermore, the seal SE encapsulates the liquid crystal layer LC between the first substrate SUB1 and the second substrate SUB2.

[0036] Polarizing plate PL1 is bonded to the underside of the first substrate SUB1. Polarizing plate PL2 is bonded to the upper surface of the second substrate SUB2. The polarization axes of polarizing plate PL1 and polarizing plate PL2 are, for example, orthogonal to each other.

[0037] The lighting device IL further comprises a diffusion sheet DS, a prism sheet PS, and a reflective sheet RS. The diffusion sheet DS is located between the display panel PNL and the light guide plate LG1. The diffusion sheet DS diffuses the light incident on it, thereby equalizing the brightness of the light.

[0038] The prism sheet PS is positioned between the diffusion sheet DS and the light guide plate LG1. The prism sheet PS focuses light emitted from, for example, the main surface 1A of the light guide plate LG1 in a third direction Z.

[0039] The prism sheet PS is composed of multiple prisms arranged continuously in the second direction Y. The multiple prisms of the prism sheet PS protrude toward the main surface 1A of the light guide plate LG1 in the third direction Z.

[0040] The prisms in the prism sheet PS have a triangular cross-sectional shape parallel to the Y-Z plane defined by the second direction Y and the third direction Z. The cross-sectional shapes of each prism in the prism sheet PS parallel to the YZ plane are similar to each other. Note that multiple (e.g., two) prism sheets PS may be superimposed in the third direction Z.

[0041] The reflective sheet RS faces the main surface 2B of the light guide plate LG2. The reflective sheet RS reflects light that leaks from the light guide plate LG2 and causes it to re-enter the light guide plate LG2.

[0042] Light guide plate LG1 has a reflective layer P1, and light guide plate LG2 has a reflective layer P2. Reflective layers P1 and P2 are layers containing multiple prisms, respectively. Reflective layer P1 is located on the main surface 1B. Reflective layer P1 is formed from the first region A1, beyond the boundary BO, to the space between the boundary BO and the side surface SF2.

[0043] The reflective layer P2 is located on the main surface 2B. The reflective layer P2 is formed from the second region A2, beyond the boundary BO, to the space between the boundary BO and the side surface SF3. The reflective layers P1 and P2 overlap in the third direction Z at and near the boundary BO. Light source unit LU1 is spaced apart from the side surface SF2, and light source unit LU2 is spaced apart from the side surface SF3.

[0044] Light L1 emitted from the light source unit LU1 is refracted by the side surface SF2 and incident on the light guide plate LG1. Of the light L1 incident on the light guide plate LG1, the light that travels toward the main surface 1A is reflected at the interface between the light guide plate LG1 and the air layer.

[0045] Furthermore, of the light L1 incident on the light guide plate LG1, the light traveling toward the main surface 1B is reflected at the interface between the light guide plate LG1 and the air layer. In this way, in the region of the second region A2 where the reflective layer P1 is not provided, the light L1 travels through the light guide plate LG1 while being repeatedly reflected.

[0046] Of the light L1 traveling within the light guide plate LG1, the light traveling from the light guide plate LG1 toward the reflective layer P1 has its direction of travel changed by the prism in the reflective layer P1, and deviates from the total internal reflection conditions of the main surface 1A, and exits from the main surface 1A.

[0047] Light emitted from the main surface 1A illuminates the display panel PNL via the prism sheet PS and the diffusion sheet DS. In other words, in the region of the second area A2 where the reflective layer P1 is not provided, the emission of light L1 from the side surface SF2 towards the display panel PNL from the light guide plate LG1 is suppressed.

[0048] Similarly, light L2 emitted from the light source unit LU2 is refracted by the side surface SF3 and incident on the light guide plate LG2. In the region of the first area A1 where the reflective layer P2 is not provided, light L2 travels through the light guide plate LG2 while being repeatedly reflected by the main surfaces 2A and 2B.

[0049] Of the light L2 traveling within the light guide plate LG2, the light traveling from the light guide plate LG2 toward the reflective layer P2 has its direction of travel changed by the prism in the reflective layer P2, and exits from the main surface 2A, deviating from the total internal reflection conditions of the main surface 2A.

[0050] Light emitted from the main surface 2A illuminates the display panel PNL via the light guide plate LG1, prism sheet PS, and diffuser sheet DS. In other words, in the region of the first area A1 where the reflective layer P2 is not provided, the emission of light L2 from the side surface SF3 towards the display panel PNL via the light guide plate LG2 is suppressed.

[0051] Thus, the display panel PNL is illuminated in the first region A1 mainly by light L1 from the light source unit LU1, and in the second region A2 mainly by light L2 from the light source unit LU2.

[0052] In the example shown in Figure 4, in the region of the second region A2 where the reflective layer P1 is not provided, the light L1 incident from the side SF2 is confined to the light guide plate LG1, and its incidence to the display panel PNL is suppressed. In the second region A2, although the light L1 from the light source unit LU1 hardly incidents on the display panel PNL, the light L2 from the light source unit LU2 illuminates the display panel PNL.

[0053] Similarly, in the region of the first area A1 where the reflective layer P2 is not provided, the light L2 incident from the side SF3 is confined to the light guide plate LG2, and its incidence to the display panel PNL is suppressed. In the first area A1, although the light L2 from the light source unit LU2 hardly incidents on the display panel PNL, the light L1 from the light source unit LU1 illuminates the display panel PNL.

[0054] Furthermore, the reflective layer P1 extends beyond the boundary BO to the second region A2, and the reflective layer P2 extends beyond the boundary BO to the first region A1. This prevents a decrease in the luminance level of the light emitted from the lighting device IL near the boundary BO.

[0055] Next, we will explain how the controller CNT controls the light-emitting elements LDR, LDG, and LDB using the light guide plate LG2 and light source unit LU2 provided in the lighting device IL.

[0056] Figure 5 is a schematic plan view of the light guide plate LG2 and light source unit LU2 shown in Figure 3. Figures 6 and 7 are timing charts showing an example of control of the light-emitting elements LDR and LDB by the controller CNT. In Figures 6 and 7, the horizontal axis T represents time, and the vertical axis A represents the current value supplied to the light-emitting elements.

[0057] In the light source unit LU2, for example, one block is composed of light-emitting elements LDR, LDG, and LDB. The light source unit LU2 includes blocks B1, B2, B3, and B4.

[0058] Blocks B1, B2, B3, and B4 are arranged in this order in the first direction X in the example shown in Figure 5. Note that the number of light-emitting elements and blocks in the light source unit LU2 may be changed as appropriate depending on the size of the display panel PNL and the light guide plate LG2.

[0059] The side surface SF3 has a first end E1 and a second end E2. The first end E1 and the second end E2 correspond to both ends of the side surface SF3. The second end E2 is located on the opposite side of the first end E1 in the first direction X.

[0060] Here, the end includes the end and the surrounding area. Block B1 faces the first end E1, and block B4 faces the second end E2. When the light-emitting elements LDR, LDG, and LDB are arranged as shown in Figure 5, the light-emitting elements LDR of block B1 and LDB of block B4 are furthest from the center line XCT. That is, the light-emitting elements LDR and LDB are located at both ends of the light source unit LU2, while the light-emitting elements LDG are not located at either end of the light source unit LU2.

[0061] The controller CNT (shown in Figure 2) is configured to individually control the illumination time of multiple light-emitting elements (LDR, LDG, LDB). Specifically, the controller CNT controls the illumination time of multiple light-emitting elements (LDR, LDG, LDB) per cycle.

[0062] Here, one cycle refers to the period from when a light-emitting element turns on until it turns on again. In Figures 6 and 7, one cycle is shown as one cycle C1. The length of one cycle C1 for the light-emitting elements LDR, LDG, and LDB is, for example, the same for each. The light-emitting elements LDR, LDG, and LDB repeatedly turn on and off with each one cycle C1.

[0063] Furthermore, the illumination time (DUTY) per cycle of C1 is sometimes called the DUTY ratio. In other words, the controller CNT controls the pulse width of the light source control signal supplied to the light-emitting elements LDR, LDG, and LDB.

[0064] Focusing on the light-emitting element LDR, the controller CNT controls the illumination time per cycle C1 for each of the multiple light-emitting element LDRs based on their positions in a first direction X. In other words, the controller CNT controls the multiple light-emitting element LDRs to each be supplied with a light source control signal of a different pulse width based on their positions in a first direction X.

[0065] For example, focusing on blocks B1 and B2, the light-emitting element LDRs of block B1 and block B2 are adjacent to each other in the first direction X, as shown in Figure 5. The light-emitting element LDR of block B1 is further away from the center line XCT (the center of the side surface SF3) than the light-emitting element LDR of block B2.

[0066] In this case, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDR in block B1 to be shorter than the illumination time per cycle C1 of the light-emitting element LDR in block B2.

[0067] In Figure 6, the illumination times per cycle C1 of the light-emitting LDRs in blocks B1 and B2 are shown as time TR1 and TR2. As described above, in Figure 6, time TR1 is shorter than time TR2 (TR1 <TR2)。

[0068] In the light-emitting element LDR, the light-emitting element LDR in block B3 is closest to the center line XCT. Here, we assume that the illumination time per cycle C1 of the light-emitting element LDR in block B3 is 100%.

[0069] In this case, the controller CNT controls the lighting time per cycle C1 of the light-emitting element LDR in block B1 to be 59.7% of that of block B3, and the lighting time per cycle C1 of the light-emitting element LDR in block B2 to be 71.2% of that of block B3.

[0070] In Figure 6, the illumination time per cycle C1 of the light-emitting element LDR in block B3 is shown by a dashed line as time TSR. As mentioned above, in Figure 6, times TR1 and TR2 are shorter than time TSR (TR1, TR2 <TSR)。

[0071] Furthermore, because the light-emitting element LDR of block B1 is further away from the center line XCT than the light-emitting element LDRs of blocks B2, B3, and B4, the controller CNT controls the light-emitting element LDR of light source unit LU2 to minimize the illumination time per cycle C1 for the light-emitting element LDR of block B1. In other words, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDR to decrease as it moves further away from the center line XCT.

[0072] Focusing on the light-emitting element LDB, the controller CNT controls the illumination time per cycle C1 for each of the multiple light-emitting element LDBs based on their positions in the first direction X.

[0073] For example, focusing on blocks B3 and B4, the light-emitting element LDBs of block B3 and block B4 are adjacent in the first direction X, as shown in Figure 5. The light-emitting element LDB of block B4 is further away from the center line XCT than the light-emitting element LDB of block B3.

[0074] In this case, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDB in block B4 to be shorter than the illumination time per cycle C1 of the light-emitting element LDB in block B3.

[0075] In Figure 7, the illumination times per cycle C1 of the light-emitting element LDBs in blocks B3 and B4 are shown as times TB3 and TB4. As mentioned above, in Figure 7, time TB4 is shorter than time TB3. <TB3)。

[0076] In the light-emitting element LDB, the light-emitting element LDB in block B2 is closest to the center line XCT. Here, we assume that the illumination time per cycle C1 for the light-emitting element LDB in block B2 is 100%. Note that the illumination time per cycle C1 for the light-emitting element LDB in block B2 is equivalent to, for example, the illumination time per cycle C1 for the light-emitting element LDR in block B3.

[0077] In this case, the controller CNT controls the lighting time per cycle C1 of the light-emitting element LDB in block B3 to be 71.7% of that of block B2, and the lighting time per cycle C1 of the light-emitting element LDB in block B4 to be 51.7% of that of block B2.

[0078] In Figure 7, the illumination time per cycle C1 of the light-emitting element LDR in block B2 is shown by a dashed line as time TSB. As mentioned above, in Figure 7, times TB3 and TB4 are shorter than time TSB (TB3, TB4 <TSB)。

[0079] Furthermore, when comparing the light-emitting element LDR and light-emitting element LDB, the difference in illumination time per cycle C1 between the light-emitting element LDB of block B3 and the light-emitting element LDB of block B4 is greater than, for example, the difference in illumination time per cycle C1 between the light-emitting element LDR of block B1 and the light-emitting element LDR of block B2.

[0080] Furthermore, because the light-emitting element LDB in block B4 is further away from the center line XCT than the light-emitting element LDBs in blocks B1, B2, and B3, the controller CNT controls the light-emitting element LDBs of the light source unit LU2 to minimize the illumination time per cycle C1 for the light-emitting element LDB in block B4. In other words, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDB to decrease as it moves further away from the center line XCT.

[0081] Focusing on the light-emitting element LDG, the controller CNT controls the illumination time of the light-emitting element LDG based on, for example, the illumination times of adjacent light-emitting elements LDR and LDB. Specifically, the controller CNT controls the illumination time of the light-emitting element LDG to prevent brightness unevenness.

[0082] Here, we assume that the illumination time (time TSB) per cycle C1 of the light-emitting element LDB in block B2 is 100%. In this case, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDG in block B1 to be 85.0% of that of block B2, the illumination time per cycle C1 of the light-emitting element LDG in block B2 to be 77.9% of that of block B2, the illumination time per cycle C1 of the light-emitting element LDG in block B3 to be 90.9% of that of block B2, and the illumination time per cycle C1 of the light-emitting element LDG in block B4 to be 81.0% of that of block B2.

[0083] The illumination time (pulse width) of the light-emitting elements LDR, LDG, and LDB is appropriately changed depending on the number of light-emitting elements, the length of the side SF2 in the first direction X, etc.

[0084] Furthermore, focusing on the current supplied to the light-emitting element LDRs, the controller CNT controls the supply of the same current value to the light-emitting element LDRs of blocks B1 through B4. In the example shown in Figure 6, the current values ​​supplied to the light-emitting element LDRs of blocks B1 and B2 are equal.

[0085] Similarly, focusing on the current supplied to the light-emitting elements LDG and LDB, the controller CNT controls the supply of the same current value to the light-emitting elements LDG and LDB of blocks B1 through B4. In the example shown in Figure 7, the current values ​​supplied to the light-emitting elements LDB of blocks B3 and B4 are equal.

[0086] The current value supplied to the light-emitting element LDR may be equal to at least one of the current values ​​supplied to the light-emitting elements LDG and LDB, or it may be equal to both of the current values ​​supplied to the light-emitting elements LDG and LDB, or they may be different from each other.

[0087] The current value is determined, for example, based on wall-plug efficiency (WPE). Here, wall-plug efficiency is the ratio of light output to the total power supplied to the light-emitting element.

[0088] Specifically, the current value is the value that maximizes the wall plug efficiency of the light-emitting elements LDR, LDG, and LDB. This allows the light-emitting elements LDR, LDG, and LDB to be used under the most efficient conditions. The supplied current value is pre-stored in a memory device (not shown), for example.

[0089] Figure 8 is a timing chart showing an example of control of the light-emitting elements LDR, LDG, and LDB by the controller CNT. In Figure 8, the timing chart of the light-emitting elements LDR, LDG, and LDB in block B4 is shown. In Figure 8, the illumination time per cycle C1 of the light-emitting element LDG is shown as time TG4.

[0090] As shown in Figure 8, the timing of the start of illumination of the light-emitting elements LDR, LDG, and LDB in one cycle C1 is, for example, simultaneous. In the example shown in Figure 8, times TR4, TG4, and TB4 are all different.

[0091] The controller CNT controls the illumination time of the light-emitting elements LDR, LDG, and LDB per cycle C1, for example, in synchronization with the control signal supplied to the display panel PNL. Focusing on the current values, the current values ​​supplied to the light-emitting elements LDR, LDG, and LDB are all equal. In blocks B1, B2, and B3, the illumination time of the light-emitting elements LDR, LDG, and LDB per cycle C1 is controlled as appropriate, similar to block B4.

[0092] As explained using Figure 3, the light emitted from multiple light-emitting elements LDR, LDG, and LDB spreads through the inside of the light guide plate LG2 while diffusing in the first region A1, mixing with the other colors, and is emitted from the second region A2.

[0093] For example, in the second region A2, brightness unevenness may be visible depending on the position in the first direction X. In particular, when the light-emitting element is a laser light source (laser diode), the directivity of the emitted light is high, making it difficult for each color to mix sufficiently inside the light guide plate LG2, and brightness unevenness may be visible. In Figure 5, a portion of the second region A2 that is spaced away from the center line XCT is shown as the third region A3 and the fourth region A4.

[0094] Focusing on the third region A3, in block B1, the distance to the third region A3 is shorter for the light-emitting element LDR than for the light-emitting element LDB. Therefore, when the output of the light-emitting elements LDR, LDG, and LDB are the same, the brightness of red tends to be higher in the third region A3 compared to blue. As a result, red is more easily visible in the third region A3.

[0095] In contrast, focusing on the fourth region A4, in block B4, the distance to the fourth region A4 is shorter for the light-emitting element LDB than for the light-emitting element LDR. Therefore, when the output of the light-emitting elements LDR, LDG, and LDB is the same, the brightness of blue tends to be higher in the fourth region A4 compared to red. As a result, blue is more easily visible in the fourth region A4.

[0096] In this embodiment, the controller CNT controls the illumination time per cycle C1 based on the position of the light-emitting elements LDR, LDG, and LDB in the first direction X. Specifically, the controller CNT controls the illumination time per cycle C1 of one of two adjacent light-emitting elements LDRs in the first direction X that is further away from the center of the side surface SF3 to be shorter than the illumination time per cycle C1 of the other light-emitting element LDR.

[0097] For example, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDR in block B1 to be shorter than the illumination time per cycle C1 of the light-emitting element LDR in block B2. This suppresses the brightness of the red light emitted from the light-emitting element LDR, thereby suppressing the occurrence of brightness unevenness in the third region A3.

[0098] Similarly, the controller CNT controls the lighting time per cycle C1 of one of two adjacent light-emitting LDBs in the first direction X that is further away from the center of the side surface SF3 to be shorter than the lighting time per cycle C1 of the other light-emitting LDB.

[0099] For example, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDB in block B4 to be shorter than the illumination time per cycle C1 of the light-emitting element LDB in block B3. This suppresses the brightness of the blue light emitted from the light-emitting element LDR, thereby suppressing the occurrence of brightness unevenness in the fourth region A4.

[0100] Furthermore, in this embodiment, the controller CNT controls the illumination time per cycle C1 of the light-emitting element LDG based on the illumination time per cycle C1 of adjacent light-emitting elements LDR and LDB, thereby further suppressing the occurrence of brightness unevenness.

[0101] Thus, in this embodiment, by individually controlling the lighting time of each period C1 of the light-emitting elements LDR, LDG, and LDB using the controller CNT, it is possible to suppress the occurrence of brightness unevenness in the second region A2 and improve the uniformity of the emitted light.

[0102] As a result, the display quality in the DSP display device can be improved. In particular, even when the light-emitting elements LDR, LDG, and LDB are laser light sources with high directivity, the uniformity of the emitted light can be improved.

[0103] In this embodiment, the controller CNT controls the light-emitting element LDR of the light source unit LU2 to minimize the illumination time per cycle C1 of the light-emitting element LDR of block B1. The controller CNT also controls the light-emitting element LDB of the light source unit LU2 to minimize the illumination time per cycle C1 of the light-emitting element LDB of block B4.

[0104] By adjusting the illumination time per cycle C1 of the light-emitting element LDR of block B1 and the light-emitting element LDB of block B4, located at both ends of the side surface SF3, the uniformity of the emitted light can be improved in areas where brightness unevenness is likely to occur.

[0105] Furthermore, one possible solution to the brightness unevenness described above is to adjust the output of the light-emitting elements. For example, increasing the current supplied to boost the output of a light-emitting element of a deficient color may reduce the efficiency of the wall plug. This is partly because the light-emitting elements generate heat as the current increases.

[0106] In this embodiment, the controller CNT controls the light-emitting elements LDR, LDG, and LDB of blocks B1 to B4 to supply a current with the same current value. Specifically, the current value is such that the wall plug efficiency of each light-emitting element LDR, LDG, and LDB is maximized.

[0107] As a result, in this embodiment, the light-emitting elements LDR, LDG, and LDB can be made to emit light under the most efficient conditions. In other words, in this embodiment, the light-emitting elements LDR, LDG, and LDB can be made to emit light under the most efficient conditions, while brightness unevenness can be suppressed.

[0108] Figures 5 and 6 illustrate an example of control by the controller CNT using the light source unit LU2. However, in the case of the light source unit LU1, the controller CNT controls the illumination time of the light-emitting elements LDR, LDG, and LDB per cycle C1, similar to the light source unit LU2.

[0109] In other words, the controller CNT can individually control the lighting time of each light-emitting element LDR, LDG, and LDB of the light source unit LU1 per cycle C1, thereby improving the uniformity of the emitted light in the first region A1.

[0110] With the display device DSP and control method configured as described above, the display quality can be improved. In addition, various other desirable effects can be obtained from this embodiment.

[0111] In this embodiment, examples are disclosed where the light-emitting elements LDR, LDG, and LDB are laser light sources, but the light-emitting elements LDR, LDG, and LDB may also be LEDs.

[0112] All display devices that a person skilled in the art can implement by appropriately modifying the design based on the display devices described above as embodiments of the present invention also fall within the scope of the present invention insofar as they encompass the gist of the present invention. Within the scope of the idea of ​​the present invention, a person skilled in the art can conceive of various modifications, and these modifications are also understood to fall within the scope of the present invention. For example, any modifications made by a person skilled in the art to add, delete, or modify components, or to add, omit, or change the conditions of the above-described embodiments, are also included within the scope of the present invention insofar as they retain the gist of the present invention.

[0113] Furthermore, any other effects and advantages brought about by the embodiments described above that are obvious from the description herein or that can be appropriately conceived by those skilled in the art are naturally considered to be brought about by the present invention. [Explanation of symbols]

[0114] 1...IC chip, 2...wiring board, C1...period, CNT...controller, DA...display area, DSP...display device, E1...first end, E2...second end, IL...lighting device, LDB, LDG, LDR...light-emitting element, LG1, LG2...light guide plate, LU1, LU2...light source unit, PNL...display panel, SF1, SF2, SF3, SF4...side, SUB1...first substrate, SUB2...second substrate.

Claims

1. A display panel that displays images, A light guide plate having sides and facing the display panel, A light source unit facing the aforementioned side and irradiating light onto the light guide plate, The system includes a controller for controlling the light source unit, The light source unit has a plurality of first light-emitting elements that emit light of the same color, arranged along the side surface. The controller controls the lighting time per cycle of two adjacent first light-emitting elements, where the period from when the light source unit is turned on until it is turned on again is defined as one cycle, so that the lighting time per cycle of one first light-emitting element that is further away from the center of the side surface is shorter than the lighting time per cycle of the other first light-emitting element. Display device.

2. The multiple first light-emitting elements are laser diodes. The display device according to claim 1.

3. The controller controls the supply of currents having the same current value to two adjacent first light-emitting elements. The display device according to claim 1.

4. The aforementioned light source unit further comprises a plurality of second light-emitting elements that emit light of the same color, The color emitted by the second light-emitting element is different from the color emitted by the first light-emitting element. The controller controls the illumination time per cycle of one of the two adjacent second light-emitting elements that is further away from the center of the side surface to be shorter than the illumination time per cycle of the other second light-emitting element. The display device according to any one of claims 1 to 3.

5. The controller controls the supply of currents having the same current value to two adjacent second light-emitting elements. The display device according to claim 4.

6. The light source unit further comprises a plurality of third light-emitting elements that emit light of the same color, The color emitted by the third light-emitting element is different from the colors emitted by the first and second light-emitting elements. The first light-emitting element, the third light-emitting element, and the second light-emitting element are arranged repeatedly along the side surface in this order. The first light-emitting element and the second light-emitting element are located at both ends of the light source unit. The display device according to claim 4.

7. The aforementioned side surface has a first end and a second end located opposite to the first end, The controller controls the plurality of first light-emitting elements to minimize the illumination time per cycle for the first light-emitting elements facing the first end, and controls the plurality of second light-emitting elements to minimize the illumination time per cycle for the second light-emitting elements facing the second end. The display device according to claim 6.

8. The controller controls the supply of currents having the same current value to the plurality of first light-emitting elements, the plurality of second light-emitting elements, and the plurality of third light-emitting elements. The display device according to claim 6.

9. A control method for a display device comprising: a display panel for displaying an image; a light guide plate having sides and facing the display panel; and a light source unit facing the sides and irradiating light onto the light guide plate, When the period from when the light source unit is turned on until it is turned on again is defined as one cycle, the lighting time per cycle of one of the two adjacent light-emitting elements of the light source unit that emit light of the same color is made shorter than the lighting time per cycle of the other light-emitting element, Control method.

10. The further includes supplying a current having the same current value to two adjacent light-emitting elements, The control method according to claim 9.

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