Display device

Abstract

Display device (1) comprising: a light source (61) configured to emit light (L); a display panel capable of receiving the light (L) from a first surface side and transmitting the light (L) to a second surface side, wherein the display panel is inclined with respect to an orthogonal plane orthogonal to an optical axis (IL) of the light (L); a light guide element (700) having an output surface (701) inclined with respect to the orthogonal plane, the light guide element (700) extending from the light source (61) to the output surface (701) and reflecting the light (L) onto the display panel, wherein a direction of inclination of the display panel with respect to the optical axis (IL) is identical to a direction of inclination of the output surface (701) with respect to the optical axis (IL), and wherein the light guide element (700) has a shape such that a distance between inner surfaces of the light guide element (700) and the optical axis (IL) increases from the light source side toward the first surface side, and the inner surfaces, which are opposite to each other in positions orthogonal to the optical axis (IL), are not uniform in curvature.

Description

Area

[0001] The present invention relates to a display device. background

[0002] So-called head-up displays (HUD), which project an image onto a transparent element such as glass, are already known (e.g., Patent Literature 1).

[0003] EP 3 575 846 A1 discloses an imaging unit for a head-up display with a matrix of light sources and collimating lenses. The light is focused via a high-resolution microlens matrix, collimated by field lenses, and then fed to an imaging unit for image display.

[0004] US 2018 / 0 217 448 A1 discloses a lighting device with a light source module consisting of multiple light sources and an opposing reflector. The reflector has multiple incident openings for the light from the light sources, opposing exit openings, and reflective surfaces extending therebetween. These each consist of multiple curved surfaces arranged along the optical axis of the light sources.

[0005] JP 2017 - 181 645 A discloses a head-up display for a vehicle that projects an image as a virtual display onto a projection component so that it is visible to the occupants. It comprises a plurality of light-emitting elements arranged side by side, a first diffusion plate for diffusing the light, an optical unit for concentrating the light in a vertical direction, and an image unit with an illumination surface on which part of the light is converted into image light. A second diffusion plate, whose scattering angle is smaller than that of the first diffusion plate, is arranged between the light concentrator and the image unit. Citation listPatent literature

[0006] Patent literature 1: JP 2014 - 178 368 A

[0007] The HUD projects an image by causing a display panel to transmit light from a light source. However, the display panel may reflect light incident from an output surface. When the light from the light source and the reflected light overlap, a phantom image may be seen due to multiple projections of the same image.

[0008] To prevent interference between the light from the light source and the reflected light, there is a method in which the display panel is tilted relative to the output direction of the light from the light source. Unfortunately, tilting the display panel relative to the output direction of the light from the light source causes the image to exhibit luminance unevenness and distortion in the tilt direction, resulting in a reduction in display quality. SummaryTechnical problem

[0009] The present invention has been made for the foregoing reasons, and its object is to provide a display device capable of achieving both restriction of the occurrence of a phantom and improvement of the display quality. Solution to the problem

[0010] To solve the above-mentioned problem and achieve the object, a display device comprises: a light source configured to emit light; a display panel capable of receiving the light from a first surface side and transmitting the light to a second surface side. The display panel is tilted with respect to an orthogonal plane orthogonal to an optical axis of the light, and a tilt direction of the display panel with respect to the optical axis is identical to a tilt direction of the output surface with respect to the optical axis. The display device further comprises a light guide member having an output surface tilted with respect to the orthogonal axis, the light guide member extending from the light source to the output surface and reflecting the light onto the display panel.The light guide member has a shape such that a distance between inner surfaces of the light guide member and the optical axis increases from the light source side toward the first surface side, and the inner surfaces opposing each other at positions orthogonal to the optical axis are not uniform in curvature. Brief description of the drawings Fig. 1 is a schematic diagram illustrating the main configuration of a display device according to an embodiment. Fig. 2 is a block diagram showing an example of the system configuration of a display unit. Fig. 3 is a circuit diagram showing an example of the configuration of a driving circuit configured to drive pixels in the display unit. Fig. Figure 4 is a schematic view of the display device capable of local dimming. Fig. 5 is a diagram illustrating aspects and arrangement of the display unit, a light source unit, a light guide unit, and a diffusion plate. Fig. 6 is a perspective view of the light guide unit. Fig. 7 is an XZ plan view of the light guide unit. Fig. 8 is an XY plan view of the light guide unit. Fig. 9 is a cross-sectional view taken along the line JJ in Fig. 8 is cut. Fig. 10 is a cross-sectional view taken along the line KK in Fig. 8 is cut. Fig. 11 is a YZ plan view of a light guide element. Fig. 12 is an XZ plan view of the light guide element. Fig. 13 is an XZ plan view of the light guide element. Fig. 14 is a perspective view of a light source. Fig. 15 is a schematic descriptive diagram for explaining a relationship between angles of a plate surface of the display unit, an output surface, and a plate surface of the diffusion plate, and a shape and luminance distribution of an image output from the display device. Description of embodiments

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The disclosure is merely an example, and suitable modifications within the gist of the invention, which can easily be devised by those skilled in the art, are included within the scope of the present invention. In order to further clarify the description, widths, thicknesses, shapes, and the like of various parts may be schematically illustrated in the drawings in comparison with actual appearances thereof. However, they are merely examples and do not limit the interpretation of the present invention. In the present specification and drawings, the same reference numerals denote components similar to those previously described with reference to the drawings already referred to, and detailed explanation thereof may be appropriately omitted.

[0012] Fig. 1 is a schematic diagram illustrating the main configuration of a display device 1 according to an embodiment. The display device 1 includes a light source unit 6 functioning as a light source device, a display unit 2 configured to output an image using light L from the light source unit 6 as a light source, and a diffusion plate 9 provided, for example, between the display unit 2 and the light source unit 6. The light L emitted from the light source unit 6 is diffused by the diffusion plate 9 and reaches the display unit 2, so that part or all of the light L passes through the display unit 2, is reflected by mirrors M and a windshield FG, and reaches a user H to be recognized as an image VI in a view of the user H.That is, the display device 1 in the embodiment functions as a head-up display (HUD) using the mirrors M and the windshield FG. Although the windshield FG is, for example, a vehicle windshield, it is sufficient that the windshield FG is a member with transparency and is located on the line of sight of the user H.

[0013] In the embodiment, plate surfaces of the display unit 2 and the diffusion plate 9 are aligned with respect to an optical axis IL (see Fig. 9 and other figures) of the light L propagating toward the plate mirror M1 from the light source unit 6 is tilted. An optical axis of external light SL entering the display unit 2 through the mirrors M can be directed in a direction different from the optical axis IL of the light L due to the tilt of the display unit 2 with respect to the optical axis IL. The generation of a phantom due to the external light SL reaching the user H again through the mirrors M after being reflected by the display unit 2 can therefore be prevented.

[0014] Although in Fig. 1 the light L after passing through the display unit 2 is guided by two mirrors M including the plate mirror M1 and a concave mirror M2, the number of mirrors may be one or equal to or more than three.

[0015] Next, the display unit 2 is described. Fig. 2 is a block diagram showing an example of the system configuration of the display unit 2. Fig. 3 is a circuit diagram illustrating an example of the configuration of a drive circuit configured to drive pixels Pix in the display unit 2. The display unit 2 in the embodiment is a transmissive liquid crystal display that outputs an image using light L as a light source. The display unit 2 is, for example, a transmissive liquid crystal display and includes an image output panel and a drive element 3, such as a display driver integrated circuit (DDIC).

[0016] The image output panel includes, for example, a transparent insulating substrate such as a glass substrate, and has a display region 21 provided on the surface of the glass substrate and formed by arranging a large number of pixels Pix comprising liquid crystal cells in a matrix (row-column configuration). Each pixel Pix includes a plurality of subpixels Vpix (see Fig. 3). The glass substrate comprises a first substrate on which a large number of pixel circuits with active elements (e.g., transistors) are arranged and formed in a matrix having a row-column configuration, and a second substrate arranged to face the first substrate with a predetermined space therebetween. The space between the first substrate and the second substrate is maintained at a predetermined space by photospacers arranged and formed at locations on the first substrate. Liquid crystal is sealed between the first substrate and the second substrate. The arrangement and sizes of the Fig. 2 are schematic and do not reflect the actual arrangement and the like.

[0017] The display region 21 has a matrix configuration (row-column configuration) in which M rows x N columns of subpixels Vpix with liquid crystal layers are arranged. In this patent specification, a row indicates a pixel row with N subpixels Vpix aligned in one direction. A column indicates a pixel column with M subpixels Vpix aligned in a direction orthogonal to the row extension direction. Values ​​of M and N are determined according to a resolution in the vertical direction and a resolution in the horizontal direction. In the display region 21, scanning lines 241, 242, 243, ... and 24 M for the respective rows along an H-direction and signal lines 251, 252, 253, ... and 25 Nare arranged for the respective columns along a V-direction in an array of M rows and N columns of the subpixels Vpix. Hereinafter, in the embodiment, the scanning lines 241, 242, 243, ... and 24 M representatively expressed as scanning lines 24 and the signal lines 251, 252, 253, ... and 25 N can be representatively expressed as signal lines 25. In the embodiment, any three of the scanning lines 241, 242, 243, ... and 24 M as scanning lines 24 m , 24 m+1 and 24 m+2 expressed (m is a natural number satisfying m ≤ M-2), and any three signal lines of the signal lines 251, 252, 253, ... and 25 N are used as signal lines 25 n , 25 n+1 and 25 n+2 expressed (n is a natural number satisfying n ≤ N-2).

[0018] The drive element 3 is a circuit mounted on the glass substrate of the image output panel, for example, by a chip-on-glass (COG) assembly. The drive element 3 is coupled to a control unit 100 through a flexible printed circuit (FPC) (not shown). The control unit 100 is a circuit configured to control operations of the display unit 2 and the light source unit 6. To be specific, the control unit 100 functions, for example, as a display control unit 101 and a light source control unit 102. The display control unit 101 outputs pixel signals for individually driving the subpixels Vpix that constitute the pixels Pix.The pixel signal is a signal obtained by combining individual gradation values ​​of, for example, red (R), green (G), blue (B), and white (W), which will be described later. The color types and the number of colors corresponding to the gradation values ​​constituting the pixel signal are optionally determined. The display control unit 101 has a function of controlling output gradation values ​​of some or all of the pixels based on the light emission amounts of the light sources 61 controlled by the light source control unit 102. The light source control unit 102 controls operations of the light sources 61 based on a display output image of the display unit 2. To be specific, the light source control unit 102 individually controls the operations of the light sources 61 constituting the light source unit 6.The control unit 100 may have a function for outputting various types of signals (e.g., a master clock, a horizontal synchronization signal, and a vertical synchronization signal) used for operations of the display unit 2. Configurations for outputting the various types of signals may be provided separately.

[0019] In the embodiment, the light source control unit 102 uses what is called one-frame delay control to control the operations of the light sources 61 based on the pixel signals for one previous frame output from the display control unit 101. One-frame delay control can dispense with a buffer for holding the pixel signals, which is necessary when attempting to control the operations of the light sources 61 in the same frame as the pixel signals. The operations of the light sources 61 can be controlled by providing the buffer in the same frame as the pixel signals.

[0020] The display unit 2 is coupled to an external input power supply (not shown) and the like. Electrical power required for the operations of the display unit 2 is supplied from the external input power supply.

[0021] To be more specific, the driver 3 drives the display unit 2 according to various signals received from, for example, the control unit 100. The control unit 100 outputs, for example, the main clock, the horizontal synchronization signal, the vertical synchronization signal, the pixel signals, and a drive command signal for the light source unit 6 to the driver 3. The driver 3 functions as a gate driver and a source driver based on these signals and the like. At least one or both of the gate driver and the source driver may be formed on a substrate using thin-film transistors (TFTs), which will be described later. In this case, it is sufficient that at least one or both of the gate driver and the source driver is electrically coupled to the driver 3.The source driver and the gate driver can be electrically coupled to different drive elements 3 or to the same drive element 3.

[0022] The gate driver holds digital data for a unit of one horizontal period according to the horizontal synchronization signal in synchronization with the vertical synchronization signal and the horizontal synchronization signal. The gate driver sequentially outputs the held digital data for one line as a vertical scanning pulse and supplies it to each of the scanning lines (scanning lines 241, 242, 243, ... and 24 M ) in the display region 21, thereby sequentially selecting the subpixels Vpix row by row. The gate driver sequentially outputs the digital data to each of the scanning lines 241, 242, 243, ... and 24 Mfor example, in the row direction from one end face to the other end face of the display region 21. The gate driver can also sequentially supply the digital data to each of the scanning lines 24 M , ... in the row direction from the other end face to one end face of the display region 21.

[0023] The source driver receives data for pixel control, which is generated, for example, based on the pixel signals. The source driver writes through signal lines 25 (signal lines 251, 252, 253, ... and 25 N ) the data for pixel control into the subpixels Vpix in a row selected by vertical scanning by the gate driver in units of one subpixel, in units of several subpixels, or in a unit of all subpixels.

[0024] Known examples of the driving method of the liquid crystal display panel include line inversion, dot inversion, and frame inversion driving methods. Line inversion is a driving method for inverting the polarities of video signals at a time cycle of 1H (H is one horizontal period) corresponding to one line (one pixel row). Dot inversion is a driving method for alternately inverting the polarities of video signals for adjacent subpixels in two intersecting directions (e.g., row and column directions). Frame inversion is a driving method for respectively inverting video signals to be written to all subpixels Vpix for each frame corresponding to one screen with the same polarity. The display unit 2 may use any of the driving methods described above.

[0025] In explaining the embodiment, the M scanning lines 241, 242, 243, ... and 24 M referred to as scan lines 24 when treated together. The scan lines 24 m , 24 m+1 and 24 m+2 in Fig. 3 are part of the M scanning lines 241, 242, 243, ... and 24 M . The N signal lines 251, 252, 253, ... and 25 N can be referred to as signal lines 25 when treated together. The signal lines 25 n , 25 n+1 and 25 n+2 in Fig. 3 are part of the N signal lines 251, 252, 253, ... and 25 N .

[0026] Wiring such as signal lines 25 that supply pixel signals to TFT elements Tr of subpixels Vpix and scanning lines 24 that drive the respective TFT elements Tr is formed in the display region 21. As described above, the signal lines 25 extend in a plane parallel to the surface of the aforementioned glass substrate and supply pixel drive data generated based on the pixel signals for outputting images to the subpixels Vpix. The subpixels Vpix include TFT elements Tr and liquid crystal elements LC. The TFT elements Tr are formed by thin-film transistors, and in this example, are formed by n-channel metal-oxide-semiconductor (MOS) TFTs.One of a source and a drain of each TFT element Tr is coupled to the signal line 25, a gate thereof is coupled to the scan line 24, and the other of the source and drain thereof is coupled to one end of the liquid crystal element LC. One end of each liquid crystal element LC is coupled to the other of the source and drain of the TFT element Tr, and the other end thereof is coupled to a common electrode COM. A drive electrode driver (not shown) applies a drive signal to the common electrodes COM. The drive electrode driver may be a structure of the drive element 3 or an independent circuit.

[0027] Each scan line 24 couples the subpixel Vpix to the other subpixels Vpix belonging to the same row in the display region 21. The scan lines 24 are coupled to the gate driver and receive the supply of vertical scanning pulses of scanning signals from the gate driver. Each signal line 25 couples the subpixel Vpix to the other subpixels Vpix belonging to the same column in the display region 21. The signal lines 25 are coupled to the source driver and receive the supply of the pixel signals from the source driver. Each common electrode COM couples the subpixel Vpix to the other subpixels Vpix belonging to the same column in the display region 21. The common electrodes COM are coupled to a drive electrode driver (not shown) and receive the supply of the drive signal from the drive electrode driver.

[0028] The gate driver applies the vertical scanning pulse to the gates of the TFT elements Tr of the subpixels Vpix through one of the scanning lines 24, thereby sequentially selecting, as the image output destination, a row (one horizontal row) of the subpixels Vpix formed in a matrix with the row-column configuration in the display region 21. The source driver supplies, through the signal lines 25, the pixel signals included in a horizontal row that the gate driver sequentially selects to the subpixels Vpix. The image output of one horizontal row is performed in these subpixels SPix according to the supplied pixel signals.

[0029] As described above, in the display unit 2, the gate driver sequentially drives the scanning line 24, thereby sequentially selecting a horizontal line. The source driver supplies the pixel signals to the subpixels Vpix corresponding to a horizontal line through the signal lines 25, thereby performing image output in the display unit 2 on a horizontal line basis. In this image output operation, the drive electrode driver applies the drive signal to the common electrodes COM corresponding to the one horizontal line.

[0030] The display region 21 has a color filter. The color filter includes a grid-shaped black matrix 76a and openings 76b. The black matrix 76a is formed to cover the outer periphery of the subpixels Vpix, as shown in Fig. 3. In other words, the black matrix 76a is arranged at boundaries between the two-dimensionally arranged subpixels Vpix, thereby having a lattice shape. The black matrix 76a is made of a material with high light absorption. The openings 76b are openings formed by the lattice shape of the black matrix 76a and are arranged at positions corresponding to the subpixels Vpix.

[0031] The openings 76b have color regions corresponding to subpixels Vpix of three colors (e.g., red (R), green (G), and blue (B)) or four colors. Specifically, the openings 76b have color regions colored with three colors of red (R), green (G), and blue (B) as an example of a first color, a second color, and a third color, and a color region of a fourth color (e.g., white (W)). In the color filter, the color regions colored with the three colors of red (R), green (G), and blue (B), for example, are periodically lined up in the openings 76b. When the fourth color is white (W), the openings 76b of white (W) are not colored by the color filter. When the fourth color is another color, the openings 76b are colored by the color filter with the color used as the fourth color.In the embodiment, the color regions of four colors are a set: the three colors of R, G and B and the fourth color (for example, white (W)) are made to correspond to the subpixels Vpix shown in . Fig. 3 to form one pixel Pix. The pixel signal supplied to one pixel Pix in the embodiment corresponds to the output of one pixel Pix having the subpixels Vpix of red (R), green (G), blue (B), and the fourth color (white (W)). In the explanation of the embodiment, red (R), green (G), blue (B), and white (W) may be simply referred to as R, G, B, and W, respectively. When the pixel Pix includes the subpixels Vpix having equal to or less than two or equal to or more than five colors, it is sufficient that digital data corresponding to the number of colors be supplied based on the original image data.

[0032] The color filter can be colored with a combination of other colors, as long as it is colored with different colors. Generally, the luminance in the green (G) color region is higher than that of the red (R) and blue (B) color regions. If the fourth color is white (W), translucent resin can be used for the color filter to create white.

[0033] When the display region 21 is viewed from the direction orthogonal to the front side, the scanning lines 24 and the signal lines 25 are arranged in regions that overlap with the black matrix 76a of the color filter. In other words, the scanning lines 24 and the signal lines 25 are hidden behind the black matrix 76a when viewed from the direction orthogonal to the front side. In the display region 21, regions where the black matrix 76a is not arranged correspond to the openings 76b.

[0034] Fig. 4 is a schematic view of the display device capable of local dimming. A display device capable of local dimming includes a display panel P capable of changing the light transmittance according to a display image, a plurality of light sources LM, and a plurality of reflectors R. The light sources LM are arranged on the opposite side (rear surface side) to a display surface of the display panel P from the display surface side. The light sources LM are arranged in a two-dimensional matrix form with a row-column configuration. The light sources LM individually emit light onto the display panel P. Reflectors R are provided for the respective light sources LM. Each reflector R is a cylindrical member that widens from the light source LM side toward the display panel P side.The light source LM is arranged on a first end face of the cylinder of the reflector R, and the display panel P is arranged on a second end face thereof. The reflector R reflects the light from the light source LM through its linear surface and guides the light toward the side of the display panel P.

[0035] The reflectors R are provided in a two-dimensional matrix form with a row-column configuration on the rear surface side of the display panel P in a manner similar to the light sources LM. The reflectors R are integrally formed to form a reflector unit RU.

[0036] Fig. 5 is a diagram illustrating aspects and arrangement of the display unit 2, the light source unit 6, a light guide unit 7, and the diffusion plate 9. In the following explanation, the direction of the light L emitted onto the display unit 2 along the optical axis IL is a Z direction. One of the two directions along a plane orthogonal to the Z direction is an X direction, and the other is a Y direction. The X direction is a direction identical to the H direction. The Y direction overlaps with the V direction in a plan view viewed from the Z direction. In the embodiment, the optical axis IL is formed by arranging a substrate 612 (see Fig. 14) included in the light source 61. To be specific, each light source 61 is configured to output the light L from a light-emitting element (e.g., a light-emitting diode (LED) 611) provided on the plate surface of the substrate 612 such that the direction orthogonal to the substrate 612 is the optical axis IL. That is, the optical axis IL is defined by arranging the substrate 612 along the XY plane as the Z direction.

[0037] The display device 1 in the embodiment includes the light guide unit 7, which functions as a reflector unit RU. The light guide unit 7 has a plurality of light guide elements 700. The light guide elements 700 function as reflectors R. That is, the light guide elements 700 are provided as cylindrical elements that extend from the light sources 61 toward the display unit 2 and cover the edges of the optical axes IL of the light L from the light sources 61. The light guide elements 700 reflect the light L from the light sources 61 through the inner surfaces thereof and guide it to the display unit. Fig. Figure 5 illustrates four light guide elements 700 aligned along an output surface 701 formed by the edges of output channels from which the light is emitted by the light sources 61. In Fig. In Figure 5 and other figures, different reference numerals are assigned to the light guide elements 700 column by column, such as light guide elements 711, 721, 731, and 741, to distinguish the four light guide elements 700 provided at different positions from each other. The output surface 701 lies along a first direction 1a. The first direction 1a is inclined with respect to the Y direction. The light source 61 is arranged at a first end of the light guide element 700. The first end of each light guide element 700 is an end portion on the opposite side to the output surface 701. Hereinafter, a second end of the light guide element 700 indicates an end portion on the side of the output surface 701. The first ends of the light guide elements 700, at which the light sources 61 are arranged, lie along the XY plane. The light sources 61 function as light sources LM. The display unit 2 functions as a display panel P.

[0038] At a first end of the light guide unit 7, the first ends of the light guide elements 700, which are aligned along the first direction la, form step-wise level differences. In Fig. 5, the positions of the first ends of the light guide elements 700, which are aligned along the first direction 1a, are shifted toward the outgoing direction (upward) of the light from the light sources 61, that is, gradually toward the second end in the order of the light guide elements 711, 721, 731, and 741. In other words, the first end of the light guide element 721 and the light source 61 provided at the light guide element 721 are located closer to the second end than the first end of the light guide element 711 and the light source 61 provided at the light guide element 711. The first end of the light guide element 731 and the light source 61 provided at the light guide element 731 are located closer to the second end than the first end of the light guide element 721 and the light source 61 provided at the light guide element 721.The first end of the light guide element 741 and the light source 61 provided on the light guide element 741 are arranged closer to the second end than the first end of the light guide element 731 and the light source 61 provided on the light guide element 731.

[0039] A power supply unit 62 is provided on the first end face of the light guide unit 7. Stepwise level differences corresponding to the light sources LM arranged to form the stepwise level differences as described above are formed on the light guide unit 7 side of the power supply unit 62. The light sources 61 provided on the first end face of the respective light guide elements 700 are coupled to the surface on the light guide unit 7 side of the power supply unit 62 to receive the supply of electric power from the power supply unit 62 and the control of the light quantities from the control unit 100. Although Fig. 5 illustrates a space between the power supply unit 62 and the light guide unit 7, but the space is not actually provided. That is, the light sources 61 provided on the first end face of the respective light guide elements 700 are arranged at any one of the levels of the light guide unit 7 side of the power supply unit 62. The surfaces of a first level 611, a second level 621, a third level 631, and a fourth level 641 on the light guide unit 7 side, which are the surfaces of the respective levels on the light guide unit 7 side, are located along the XY plane. The light source 61 provided on the light guide element 711 is arranged at the first level 611. The light source 61 provided on the light guide element 721 is arranged at the second level 621. The light source 61 provided on the light guide element 731 is arranged at the third level 631.The light source 61 provided on the light guide element 741 is arranged on the fourth level 641.

[0040] The display unit 2 and the diffusion plate 9 are arranged on the output surface 701 side of the light guide unit 7. The diffusion plate 9 is inserted between the display unit 2 and the light guide unit 7. A plate surface 201 of the display unit 2 lies along a second direction 1b. A plate surface 901 of the diffusion plate 9 lies along a third direction 1c. The second direction 1b and the third direction 1c are inclined with respect to the Y direction. In the embodiment, the inclination directions and inclination angles of the first direction 1a, the second direction 1b, and the third direction 1c are identical with respect to the Y direction. The first direction 1a, the second direction 1b, and / or the third direction 1c may be different from another direction.In this case, the difference between the inclination angle of the second direction Ib with respect to the Y direction and the inclination angle of the third direction Ic with respect to the Y direction is desirably within a range of ±2%. When one of them (the inclination angle of the second direction Ib with respect to the Y direction or the inclination angle of the third direction Ic with respect to the Y direction) is 100%, "2%" is the ratio of the other.

[0041] Fig. 6 is a perspective view of the light guide unit 7. Fig. 7 is an XZ plan view of the light guide unit 7. The light guide unit 7 has the light guide elements 700 aligned along the X direction. Fig. 6 and Fig. 7 illustrates a row of the light guide elements 700 formed by eight light guide elements 700 aligned in the X direction, such as the light guide element 711, 712, 713, 714, 715, 716, 717, and 718. In positions of the light guide elements 721, 731, and 741 in columns different from that of the light guide element 711, eight light guide elements 700 aligned in the X direction also form the rows of the light guide elements 700, such as the light guide element 721, ... and 728, light guide elements 731, ... and 738, and light guide elements 741, ... and 748. The number of light guide elements 700 aligned along the X direction may be equal to or less than seven, or equal to or more than nine. Likewise, the number of light guide elements 700 aligned along the first direction la may be equal to or less than three or equal to or more than five.The number and arrangement of the light sources 61 correspond to the number and arrangement of the light guide elements 700.

[0042] The output surface 701, which with respect to Fig. 5, the surface along the edges of the second ends of the light guide elements 700 arranged in the row and column directions (see Fig. 6 and Fig. 7). As described above, the output surface 701 lies along the first direction la and is inclined with respect to the Y direction. In Fig. 6, the inclination angle of the first direction la with respect to the Y direction is an angle θa. The angle θa is, for example, 13°. However, this angle is merely an example, is not limited to this, and can be changed as appropriate.

[0043] Fig. 8 is an XY plan view of the light guide unit 7. Fig. 9 is a cross-sectional view taken along the line JJ in Fig. 8. The cross section cut along the line JJ is a cross section of the row of light guide elements 700 formed by the light guide elements 721, ... and 728 when cut along the XZ plane, and the same applies to cross sections of the other rows of light guide elements 700 when cut along the XZ plane. Fig. 10 is a cross-sectional view taken along the line KK in Fig. 8. The cross section cut along the line KK is a cross section of the column of light guide elements 700 formed by the light guide elements 714, ... and 744 when cut along the YZ plane, and the same applies to cross sections of the other columns of light guide elements 700 when cut along the YZ plane.

[0044] The light guide member 700 includes a reflection unit 750. The reflection unit 750 covers the inner surface of the cylinder formed by the light guide member 700. The reflection unit 750 is provided to further increase the reflectivity of the light L from the light source 61. It is sufficient for the reflection unit 750 to be a member having a higher reflectivity of the light L than that of the resin as the material of the light guide member 700 in the embodiment. The reflection unit 750 may be, for example, a plate-like reflection member adhered to the inner surface of the light guide member 700, a metal or compound firmly adhered to the inner surface of the light guide member 700 by a coating, deposition, or the like method, or a member provided on the inside of the light guide member 700 by another method.

[0045] The reflection unit 750 includes a first inner surface portion 751 and a second inner surface portion 752 that oppose each other in the Y direction, and a third inner surface portion 753 and a fourth inner surface portion 754 that oppose each other in the X direction. The extension length of the second inner surface portion 752 in the Z direction is greater than that of the first inner surface portion 751. The difference in the extension length in the Z direction between the first inner surface portion 751 and the second inner surface portion 752 is set depending on the first direction 1a as an upward direction from the second inner surface portion 752 toward the first inner surface portion 751. The third inner surface portion 753 and the fourth inner surface portion 754 are linearly symmetrical to each other with respect to the Y direction.That is, a straight line connecting the first end face of the third inner surface portion 753 and the first end face of the fourth inner surface portion 754 lies along the X direction. A straight line connecting the second end face of the third inner surface portion 753 and the second end face of the fourth inner surface portion 754 lies along the X direction. A straight line connecting the first end face of the first inner surface portion 751 and the first end face of the second inner surface portion 752 lies along the Y direction.

[0046] A joint between the first inner surface portion 751 and the second inner surface portion 752, a joint between the second inner surface portion 752 and the third inner surface portion 753, a joint between the third inner surface portion 753 and the fourth inner surface portion 754, and a joint between the fourth inner surface portion 754 and the first inner surface portion 751 in the embodiment have curved shapes. However, these joints may be joints forming angles, and specific shapes thereof may be appropriately changed. The same applies to the shapes of the light guide elements 700 arranged on the outer peripheral sides of these joints.

[0047] In the embodiment, the resin used as the material of the light-guiding elements 700 is black resin. Black resin absorbs light more easily than resins of other colors. Therefore, the light L from the light sources 61 can be prevented from passing through the light-guiding elements 700 and escaping to the outside.

[0048] Each light guide element 700 widens from a bottom portion B toward a front end portion T. In other words, the light guide element 700 has a shape such that a distance between the inner surfaces and the optical axis IL increases from the light source 61 side (the first end face) toward the output surface 701 side (the second end face). Such a shape functions as a mold for causing the reflection direction of the light L from the light source 61 to be along the Z direction and can be used as a draft angle when the light guide element 700 is formed by injection molding. In the wall surfaces constituting the cylinder of the light guide element 700, the thickness of the front end portion T, which is relatively close to the second end face, is smaller than the thickness of the bottom portion B, which is relatively close to the first end face.This configuration can further reduce the probability of a sink mark being generated in the front end portion T, which is formed as a larger cylindrical frame body than the lower portion B.

[0049] Fig. 11 is a YZ plan view of the light guide element 700. Fig. 12 and Fig. 13 are XZ plan views of the light guide element 700. Each light guide element 700 includes a first wall surface portion 761 and a second wall surface portion 762 opposite each other in the Y direction, and a third wall surface portion 763 and a fourth wall surface portion 764 opposite each other in the X direction. In a manner similar to the relationship between the second inner surface portion 752 and the first inner surface portion 751, an extension length Z2 of the second wall surface portion 762 in the Z direction is greater than an extension length Z1 of the first wall surface portion 761 in the Z direction. The difference in the extension length in the Z direction between the first wall surface portion 761 and the second wall surface portion 762 is determined depending on the first direction 1a.The third wall surface portion 763 and the fourth wall surface portion 764 are linearly symmetrical to each other with respect to the Y direction, in a manner similar to the relationship between the third inner surface portion 753 and the fourth inner surface portion 754. That is, a straight line connecting the first end face of the third wall surface portion 763 and the first end face of the fourth wall surface portion 764 lies along the X direction. A straight line connecting the first end face of the first wall surface portion 761 and the first end face of the second wall surface portion 762 lies along the Y direction. That is, as described above, the first end face of the light guide element 700 lies along the XY plane. A straight line connecting the second end face of the third wall surface portion 763 and the second end face of the fourth wall surface portion 764 lies along the X direction. Fig. 12 is a view viewed from the side of the first wall surface portion 761. Fig. 13 is a view viewed from the side of the second wall surface portion 762.

[0050] A first intermediate portion P3 of the first wall surface portion 761 and a first intermediate portion P4 of the second wall surface portion 762 in Fig. 11 have the same distance from the optical axis IL. However, an interval Z3 between the first end of the light-guiding element 700 and the first intermediate section P3 in the Z direction is different from an interval Z4 between the first end of the light-guiding element 700 and the first intermediate section P4 in the Z direction. In Fig. 11, Z4 > Z3 is satisfied. When a line connecting the first intermediate portion P3 and the first intermediate portion P4 is drawn at the third wall surface portion 763, the line has an inclination in a direction identical to the first direction 1a with respect to the Z direction. This indicates that a curvature of the shape that widens from the first end face of the light guide member 700 toward the second end face thereof is different between the first wall surface portion 761 and the second wall surface portion 762.A relationship between a second intermediate portion P5 of the first wall surface portion 761 and a second intermediate portion P6 of the second wall surface portion 762, and a relationship between a third intermediate portion P7 of the first wall surface portion 761 and a third intermediate portion P8 of the second wall surface portion 762 are similar to the relationship between the first intermediate portion P3 and the first intermediate portion P4. Thus, in the light guide element 700, the portions opposing each other at positions orthogonal to the optical axis IL are not uniform in curvature.

[0051] The reflection unit 750 provided on the inner surfaces of the light guide member 700 also has a difference in curvature due to the unevenness of the curvature in the inner surfaces facing each other at positions orthogonal to the optical axis IL, in a manner similar to the light guide member 700. The difference in curvature is set so that the difference in reflection of the light L due to the difference in the distance from the first end to the second end between the first inner surface portion 751 and the second inner surface portion 752 is reduced. That is, the difference in curvature is set so that a luminance distribution of the light L emitted from the output channel is closer to uniform between the first inner surface portion 751 side and the second inner surface portion 752 side with the optical axis IL interposed therebetween.

[0052] A distance to the optical axis IL does not need to be the same between the second end P1 of the first wall surface portion 761 and the second end P2 of the second wall surface portion 762. The optical axis IL may be offset from the center of the output channel at the second end of the light guide element 700 in the Y direction, which is surrounded by the inner surfaces of the first wall surface portion 761, the second wall surface portion 762, the third wall surface portion 763, and the fourth wall surface portion 764, that is, the first inner surface portion 751, the second inner surface portion 752, the third inner surface portion 753, and the fourth inner surface portion 754.For example, the optical axis IL may be displaced toward the first inner surface portion 751 with respect to a line (intermediate line) along the Z direction, from which distances to the second end P1 and the second end P2 in the Y direction are equal to each other. With respect to the X direction, the optical axis IL is desirably arranged on a line with respect to which the third inner surface portion 753 and the fourth inner surface portion 754 are linearly symmetrical to each other.

[0053] Fig. 14 is a perspective view of the light source 61. Each light source 61 includes an LED 611, the substrate 612, and a diffusing element 613. The LED 611 is a light-emitting diode that emits, for example, white light. The LED 611 is turned on with electric power supplied from the power supply unit 62 and emits light. The substrate 612 is a substrate on which wiring to be coupled to the LED 611 is mounted. The substrate 612 is installed at any one of the levels of the power supply unit 62 to couple the LED 611 and the power supply unit 62. With respect to a positional relationship between the first end and the second end of the light guide element 700, the substrate 612 is arranged on the first end side of the LED 611. The LED 611 emits light toward the second end side.The diffusing element 613 is a light guide element with transparency and is provided to cover the second end faces of the LED 611 and the substrate 612, and has the same configuration as that of the diffusing plate 9. The diffusing element 613 diffuses the light from the LED 611 in a planar shape and outputs it from the second end face.

[0054] In the embodiment, the planar XY shapes of the substrate 612 and the diffusing element 613 are rectangular shapes each having four sides, including two sides opposite each other along the X direction and the other two sides opposite each other along the Y direction. The inner shape of the cylinder at the first end of the light guide element 700 corresponds to the outer shape of the planar XY shape of the light source 61. Consequently, the light source 61 has an emission surface with a rectangular shape. The light guide element 700 is formed to have a shape along the XY plane that includes four sides (the first wall surface portion 761, the second wall surface portion 762, the third wall surface portion 763, and the fourth wall surface portion 764) along the four sides of the light emission surface (see Fig. 8).

[0055] The substrate 612 in the embodiment is a black substrate on at least the second end face. That is, the color of the substrate 612 on at least the side where the LED 611 is provided is black. Therefore, the optical axis IL of the LED 611 can be prevented from passing through the substrate 612 and exiting to the first end face. The substrate 612 may be formed such that only the surface of the substrate 612 on the second end face before a wiring pattern and the like are formed is black, or a larger area including the surface of the substrate 612 on the first end face is black.

[0056] Although in Fig. 14 one LED 611 is provided in a light source 61, several LEDs 611 can be provided in a light source 61.

[0057] The following describes the effects of the embodiment with reference to Fig. 15 described. Fig. 15 is a schematic descriptive diagram for explaining a relationship between angles of the plate surface 201 of the display unit 2, the output surface 701 and the plate surface 901 of the diffusion plate 9, and a shape and luminance distribution of an image output from the display device.

[0058] In an example in Fig. 15, the output surface 701, the disk surface 201, and the disk surface 901 are provided in states where they are inclined in the first direction 1a, the second direction 1b, and the third direction 1c, respectively, with respect to the Y direction, as in the aforementioned embodiment. In this example, the image VI is considered a rectangular image in which brightness imbalance is completely avoided.

[0059] In contrast, in a first comparative example in Fig. 15, only the disk surface 201 is inclined in the second direction 1b with respect to the Y direction, whereas the output surface 701 and the disk surface 901 are provided to lie along the Y direction. In the first comparative example, the image VI is considered to be a trapezoidal image having one side whose length is relatively short and the opposite side whose length is relatively long. One side corresponds to the side where a distance between the disk surface 201 and the disk surface 901 is relatively short, and the opposite side corresponds to the side where the distance between the disk surface 201 and the disk surface 901 is relatively long. That is, in the first comparative example, distortion is generated in the image.

[0060] In a second comparison example in Fig. 15, the disk surface 201 is inclined in the second direction 1b with respect to the Y direction, the disk surface 901 is inclined in the third direction 1c with respect to the Y direction, and the output surface 701 is provided to lie along the Y direction. In the second comparative example, the image VI is considered as an image having a portion on one side that is relatively brighter and a portion on the opposite side that is relatively darker. One side of the image corresponds to the side where the distance between the disk surface 201 and the output surface 701 is relatively short, and the opposite side of the image corresponds to the side where the distance between the disk surface 201 and the output surface 701 is relatively long. That is, in the second comparative example, an imbalance of brightness is generated in the image.

[0061] As described above, in the light guide element 700, the inner surfaces that are opposed to each other at positions orthogonal to the optical axis IL are not uniform in curvature. With influences from this, when the optical axis is arranged on the intermediate line of the output surface 701 in the Y direction, an imbalance in luminance is generated. To be precise, the luminance of the light emitted from the first wall surface portion 761 side with respect to the optical axis IL is significantly higher than the luminance of the light emitted from the second wall surface portion 762 side. When the optical axis IL is arranged in a position closer to the second wall surface portion 762 (left side in Fig. 11) with respect to the intermediate line, a similar imbalance of luminance is also created.

[0062] Shifting the position of the optical axis IL to the side of the first wall surface portion 761 (right side in Fig. 11) with respect to the intermediate line can prevent the generation of luminance imbalance. In other words, shifting the position of the optical axis IL to the second end P1 side (right side in Fig. 11) with respect to the intermediate line can prevent the generation of luminance imbalance.

[0063] As described above, according to the embodiment, the panel surface 201 of the display unit 2 is tilted with respect to the XY plane. Therefore, the generation of a ghost due to multi-projection caused by the superposition of the light from the light source and the reflected light can be prevented. The output surface 701 of the light guide unit 7 is tilted with respect to the XY plane. The tilt direction of the panel surface 201 with respect to the optical axis IL along the Z direction is the same as the tilt direction of the output surface 701. This can provide the image VI, which is considered a rectangular image in which the brightness imbalance is completely prevented. Consequently, the embodiment can achieve both restriction of the occurrence of a ghost and improvement of the display quality.

[0064] Each light guide element 700 has a shape that widens toward the output surface 701 side, so that the distance between the inner surfaces and the optical axis IL increases from the light source 61 side toward the output surface 701 side, and the inner surfaces facing each other at positions orthogonal to the optical axis IL are not uniform in curvature. Therefore, the difference in reflection of light L due to the difference in the distance from the first end to the second end between the first inner surface portion 751 and the second inner surface portion 752 can be reduced by the difference in curvature.

[0065] The optical axis IL is shifted from the intermediate line in a predetermined direction. The predetermined direction is a direction (right side in Fig.11) toward the second end P1 side, which is one of the second end P1 side and the second end P2 side, arranged so as to sandwich the intermediate line therebetween, and on which the distance between the edge of the output channel and the light source 61 is relatively small due to the inclination in the first direction 1a. Therefore, the difference in the reflection of the light due to the difference in the distance from the first end to the second end between the first inner surface portion 751 and the second inner surface portion 752 can be further reduced.

[0066] Each light source 61 has a rectangular light-emitting surface. The light guide element 700 is formed to have a shape along the XY plane that includes four sides along the four sides of the light-emitting surface. The light source unit 6, which is preferred for illuminating the display unit 2 with the rectangular display region 21, can thus be created.

[0067] The plurality of light sources 61 and the plurality of light guide elements 700 are provided. The light guide elements 700 are individually provided for the respective light sources 61. The light sources 61, which are aligned along the first direction 1a, are arranged in a stepwise manner. With this arrangement, the output surfaces of the light L from the light sources 61 can be made along the XY plane to establish the optical axes IL along the Z direction, and the light sources 61 can be arranged along the first direction 1a. The arrangement of the light sources 61 for local dimming in the direction along the first direction 1a can be achieved.

[0068] The light sources 61 are aligned along the X-direction. The arrangement of the light sources 61 for local dimming in the X-direction can therefore be achieved.

[0069] The diffuser plate 9, which is arranged between the light guide unit 7 and the display unit 2 and diffuses light, is included. The display region 21 can thus be evenly illuminated.

[0070] The diffusion plate 9 is tilted with respect to the XY plane in a tilt direction identical to that of the display unit 2. The difference in the angle with respect to the XY plane between the second direction 1b and the third direction 1c is within ±2%. This further prevents the generation of brightness imbalance in the image VI.

[0071] The light guide elements 700 are made of black resin. Consequently, the light L from the light sources 61 can be prevented from passing through the light guide elements 700 and exiting to the outside. This means that a reduction in display quality due to light leakage can be prevented.

[0072] The light guide elements 700 have the reflection units 750 covered by the elements with higher reflectivity of the light L than the black resin. Therefore, both the restriction of light leakage with the black resin and the guidance of the light L by the reflection units 750 can be achieved.

[0073] The light guide elements 700 are formed such that the thicknesses of the front end portions T are smaller than those of the lower portions B. This can further reduce the possibility of a sink mark being generated in the front end portions T, which are formed as large cylindrical frame bodies compared to the lower portions B.

[0074] The light guide elements 700 constituting the light guide unit 7 have the same shape. The light guide elements 700 can be manufactured using the same mold or the like, and the light guide elements 700 can be combined to form the light guide unit 7. Consequently, the light guide unit 7 can be manufactured more easily.

[0075] The above-mentioned embodiment is merely an example and can be modified to an extent as appropriate without departing from the technical characteristics of the present invention. For example, although the display unit 2 in the embodiment is a display panel enabling color display, the display unit 2 may be a monochrome display panel. In the embodiment, the light sources 61 and the light guide elements 700 are arranged in a matrix having the row-column configuration. Alternatively, the light sources 61 and the light guide elements 700 may be arranged in one of the X direction and the first direction 1a, or a single light source 61 and a single light guide element 700 may be provided.

[0076] Other operational effects provided by the aspect described in the embodiment, which are apparent from the description of the present specification or which can be conveniently arrived at by one skilled in the art, should be interpreted as provided by the present invention. List of reference symbols 1 DISPLAY DEVICE 2 DISPLAY UNIT 6 LIGHT SOURCE UNIT 7 FIBER OPTIC UNIT 9 Spreader plate 61 LIGHT SOURCE 611 LED 612 SUBSTRATE 62 POWER SUPPLY UNIT 700 Light guide element 701 EXIT SURFACE 750 REFLECTION UNIT B LOWER SECTION FG WINDSHIELD IL OPTICAL AXIS L LIGHT M SPIEGEL SL EXTERNAL LIGHT T FRONT END SECTION VI IMAGE

Claims

[1] Display device (1) comprising: a light source (61) configured to emit light (L); a display panel capable of receiving the light (L) from a first surface side and transmitting the light (L) to a second surface side, wherein the display panel is inclined with respect to an orthogonal plane orthogonal to an optical axis (IL) of the light (L); a light guide element (700) having an output surface (701) inclined with respect to the orthogonal plane, the light guide element (700) extending from the light source (61) to the output surface (701) and reflecting the light (L) onto the display panel, wherein a direction of inclination of the display panel with respect to the optical axis (IL) is identical to a direction of inclination of the output surface (701) with respect to the optical axis (IL), and wherein the light guide element (700) has a shape such that a distance between inner surfaces of the light guide element (700) and the optical axis (IL) increases from the light source side toward the first surface side, and the inner surfaces, which are opposite to each other in positions orthogonal to the optical axis (IL), are not uniform in curvature. [2] Display device (1) according to claim 1, wherein the optical axis (IL) is shifted in a predetermined direction from a center of the output surface (701) having a rectangular shape, and wherein the predetermined direction is a direction along the orthogonal plane and is directed toward a side on which a distance between an edge of the output surface (701) and the light source (61) is relatively small due to the inclination of the output surface (701) with respect to the orthogonal plane. [3] Display device (1) according to claim 1 or 2, wherein the light source (61) has a light emitting surface with a rectangular shape, and wherein the light guide element (700) is formed to have a shape lying along the orthogonal plane and having four sides along four sides of the light emitting surface. [4] Display device (1) according to one of claims 1 to 3, wherein several of the light sources (61) and several of the light guide elements (700) are provided, wherein the light sources (61) aligned in the inclination direction are arranged in a stepwise manner along the inclination direction, and wherein the light-guiding elements (700) are provided for the respective light sources (61). [5] Display device (1) according to one of claims 1 to 4, comprising a scattering plate (9) arranged between the light-guiding element (700) and the display panel and scattering the light (L). [6] Display device (1) according to claim 5, wherein the diffusing plate (9) is inclined in a direction of inclination identical to the direction of inclination of the display panel with respect to the orthogonal plane, and wherein the difference in angle with respect to the orthogonal plane between an inclination angle of the display panel and an inclination angle of the scattering plate (9) is within ±2%.

Images