Display devices and head-up displays

Abstract

To provide a display device that can reduce power consumption. [Solution] The display device 1 includes a light source device 10 that emits emitted light SL including a first linearly polarized light PL1 and a second linearly polarized light PL2 orthogonal to the first linearly polarized light PL1; a liquid crystal display panel 20 that is inclined with respect to the optical axis of the emitted light SL and has a polarizing reflector 24 that receives the emitted light SL, transmits the first linearly polarized light PL1, and reflects the second linearly polarized light PL2; and a reflector 30 that reflects the second linearly polarized light PL2 reflected by the polarizing reflector 24 toward the liquid crystal display panel 20. The reflector 30 includes a first plate portion 31 that receives the second linearly polarized light PL2 reflected by the polarizing reflector 24 and gives the incident light a phase difference of 1 / 4 wavelength; and a second plate portion 32 that reflects the light transmitted through the first plate portion 31 toward the liquid crystal display panel 20 via the first plate portion 31.

Description

Technical Field

[0001] The present disclosure relates to a display device and a head-up display.

Background Art

[0002] Patent Document 1 discloses, as an example of a display device, a head-up display device that projects an image onto a translucent body such as a front glass and allows a user to visually recognize a virtual image. The display device of Patent Document 1 includes a light-emitting element, a liquid crystal display panel that transmits the light of the light-emitting element and projects an image, and a reflector that reflects the light that has passed through the liquid crystal display panel toward the front glass. The liquid crystal display panel includes a liquid crystal cell and two polarizing plates on both sides of the liquid crystal cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the display device of Patent Document 1, the amount of light of the light-emitting element (light source device) is reduced by the polarizing plate. Therefore, in order for a user to visually recognize an image of the display device, the amount of light of the light source device needs to be relatively large. Therefore, the power consumption of the light source device is relatively large. Further, when the display device is used as, for example, a head-up display for a vehicle, in order for a user to visually recognize a virtual image during the day with sunlight, the amount of light and the power consumption of the light source device become even larger. On the other hand, there is a desire to suppress the power consumption of the display device.

[0005] An object of the present disclosure is to provide a display device and a head-up display capable of suppressing power consumption.

Means for Solving the Problems

[0006] The display device of this disclosure includes a light source device that emits light including a first linearly polarized light and a second linearly polarized light orthogonal to the first linearly polarized light; a liquid crystal display panel that is inclined with respect to the optical axis of the emitted light and has a polarizing reflector that receives the emitted light, transmits the first linearly polarized light, and reflects the second linearly polarized light; and a reflector that reflects the second linearly polarized light reflected by the polarizing reflector toward the liquid crystal display panel, wherein the reflector includes a first plate portion that receives the second linearly polarized light reflected by the polarizing reflector and gives the incident light a phase difference of 1 / 4 wavelength; and a second plate portion that reflects the light transmitted through the first plate portion toward the liquid crystal display panel via the first plate portion.

[0007] Furthermore, the head-up display of the present disclosure includes a light source device that emits light including a first linearly polarized light and a second linearly polarized light orthogonal to the first linearly polarized light; a liquid crystal display panel that is inclined with respect to the optical axis of the emitted light and has a polarizing reflector that receives the emitted light, transmits the first linearly polarized light, and reflects the second linearly polarized light; and a reflector that reflects the second linearly polarized light reflected by the polarizing reflector toward the liquid crystal display panel, wherein the reflector includes a first plate portion that receives the second linearly polarized light reflected by the polarizing reflector and gives the second linearly polarized light a phase difference of 1 / 4 wavelength; and a second plate portion that reflects the light transmitted through the first plate portion toward the liquid crystal display panel via the first plate portion. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a plan view of a display device according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a side view of the display device along the X direction. [Figure 3] Figure 3 is a plan view of the light source device. [Figure 4] Figure 4 is a cross-sectional view of the light source device. [Figure 5] Figure 5 is a cross-sectional view of a liquid crystal display panel. [Figure 6] Figure 6 is a cross-sectional view of the reflector. [Figure 7]Figure 7 shows the reflector as viewed along a direction perpendicular to the surface of the reflector. [Figure 8] Figure 8 is a schematic cross-sectional view of a display device showing the positional relationship between the light source, liquid crystal display panel, and reflector. [Figure 9] Figure 9 is a schematic diagram of a head-up display according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below. Furthermore, the components described below include those that are readily conceivable to those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate.

[0010] Furthermore, the disclosure is merely an example, and any modifications that a person skilled in the art could easily conceive of while maintaining the spirit of this disclosure are naturally included within the scope of this disclosure. In addition, drawings may schematically represent the width, thickness, shape, etc. of each part in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In addition, in this specification and each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0011] The X, Y, and Z directions shown in the drawings are orthogonal to each other and correspond to the width, depth, and height directions of the display device 1, respectively. Note that the X, Y, and Z directions are examples, and this disclosure is not limited to these directions. In this specification, "plan view" means viewing the display device 1 along the Z direction. Also, "side view" means viewing the display device 1 along a direction perpendicular to the Z direction (i.e., a direction parallel to the X and Y directions).

[0012] <Display device 1> FIG. 1 is a plan view of a display device 1 according to an embodiment of the present disclosure. FIG. 2 is a side view of the display device 1 along the X direction.

[0013] The display device 1 is applied to, for example, a vehicle navigation system. The display device 1 includes a light source device 10, a liquid crystal display panel 20, and a reflector 30.

[0014] The light source device 10 emits emitted light SL. The optical axis of the emitted light SL is along the Z direction. The emitted light SL includes a first linearly polarized light PL1 and a second linearly polarized light PL2. The first linearly polarized light PL1 is a linearly polarized light having a first polarization direction perpendicular to the Z direction and along the X direction. The second linearly polarized light PL2 is a linearly polarized light having a second polarization direction perpendicular to the Z direction and along the Y direction. The first polarization direction and the second polarization direction are perpendicular to each other.

[0015] Hereinafter, in this specification, a linearly polarized light along a plane (ZX plane) perpendicular to the optical axis and parallel to the Z direction and the X direction is referred to as S-polarized light. Also, a linearly polarized light along a plane (ZY plane) perpendicular to the optical axis and parallel to the Z direction and the Y direction is referred to as P-polarized light. The first linearly polarized light PL1 emitted from the light source device 10 corresponds to S-polarized light, and the second linearly polarized light PL2 emitted from the light source device 10 corresponds to P-polarized light. The "S" in the parentheses attached to the symbol of the arrow representing light in the drawings means that the light is S-polarized light. Similarly, the "P" in the parentheses means that the light is P-polarized light.

[0016] FIG. 3 is a plan view of the light source device 1. FIG. 4 is a cross-sectional view of the light source device 1.

[0017] The light source device 1 includes a housing 11, a plurality of light emitters 12, and an optical element 13. The plurality of light emitters 12 and the optical element 13 are housed in the housing 11.

[0018] The plurality of light emitters 12 are arranged on a substrate 14 located at the bottom of the housing 11. The plurality of light emitters 12 are arranged in a row along the X direction. The light emitter 12 is, for example, an LED (Light Emitting Diode). The light emitter 12 emits light L toward the optical element 13.

[0019] When the light source device 10 is viewed along the X direction, the optical element 13 makes the light L of the light emitter 12 into parallel light. The optical element 13 is configured by combining, for example, a plurality of convex lenses. Note that the optical element 13 may be an optical element that makes the light of the light emitter 12 into parallel light when the light source device 10 is viewed along the X direction and the Y direction. The parallel light emitted from the optical element 13 corresponds to the emitted light SL of the light source device 10.

[0020] The liquid crystal display panel 20 shown in FIGS. 1 and 2 is a transmissive liquid crystal display. Note that the liquid crystal display panel 20 may be an organic EL display or an inorganic EL display. The liquid crystal display panel 20 has a display surface 20a including an effective region AA where an image is displayed. The effective region AA is rectangular in plan view. Hereinafter, the thickness direction of the liquid crystal display panel 20 is defined as the first direction D1, and the direction orthogonal to the first direction D1 and the X direction is defined as the second direction D2.

[0021] The liquid crystal display panel 20 is inclined with respect to the optical axis of the emitted light SL. Specifically, the liquid crystal display panel 20 is inclined around a virtual axis VA along the first polarization direction of the first linearly polarized light PL1. The virtual axis VA extends along the X direction. The angle of the liquid crystal display panel 20 with respect to the plane (XY plane) parallel to the X direction and the Y direction is referred to as an inclination angle θ. The inclination angle θ corresponds to the angle between the Y direction and the second direction D2. The inclination angle θ is approximately 10° or more and 70° or less.

[0022] FIG. 5 is a cross-sectional view of the liquid crystal display panel 20. As shown in FIGS. 2 and 5, the liquid crystal display panel 20 includes a first substrate 21, a second substrate 22, a liquid crystal layer 23, a polarization reflection plate 24, and a polarizing plate 25. The first substrate 21 and the second substrate 22 face each other. The liquid crystal layer 23 is disposed between the first substrate 21 and the second substrate 22.

[0023] The first substrate 21 is located on the -Z side of the second substrate 22 (opposite to the side indicated by the arrow in the Z direction (+Z side)). The first alignment film AL1, insulating film IL, common electrode CE, and multiple pixel electrodes PE are arranged on the +Z side surface of the first substrate 21. The first alignment film AL1 is in contact with the liquid crystal layer 23. The orientation direction of the first alignment film AL1 is along the first polarization direction of the first linearly polarized light PL1.

[0024] The common electrode CE is placed between the first substrate 21 and the insulating film IL. Multiple pixel electrodes PE are placed between the insulating film IL and the first alignment film AL1.

[0025] Multiple pixel electrodes PE overlap with the effective region AA in the Z direction. Furthermore, multiple pixel electrodes PE overlap with a single common electrode CE in the Z direction via an insulating film IL. Thus, the common electrode CE and the pixel electrodes PE are arranged on the first substrate 21. In other words, the liquid crystal display panel 20 is a transverse electric field type liquid crystal display.

[0026] A second alignment film AL2 is positioned on the -Z side of the second substrate 22. The second alignment film AL2 is in contact with the liquid crystal layer 23. The orientation direction of the second alignment film AL2 is perpendicular to the orientation direction of the first alignment film AL1 and aligns with the second polarization direction of the second linearly polarized film PL2.

[0027] The liquid crystal layer 23 contains multiple liquid crystal molecules LM. The initial orientation of the liquid crystal molecules LM is regulated by the first orientation layer AL1 and the second orientation layer AL2.

[0028] The polarizing reflector 24 is positioned on the -Z side of the first substrate 21. Outgoing light SL is incident on the polarizing reflector 24. The polarizing reflector 24 has a transmission axis that transmits the first linearly polarized light PL1. In other words, the transmission axis of the polarizing reflector 24 is aligned with the X direction in a plan view. The polarizing reflector 24 also reflects the second linearly polarized light PL2 on its -Z side surface (hereinafter referred to as the first reflective surface 24a). The first reflective surface 24a corresponds to the -Z side surface (back) of the liquid crystal display panel 20.

[0029] The polarizing plate 25 is positioned on the +Z side of the second substrate 22. The transmission axis of the polarizing plate 25 is perpendicular to the transmission axis of the polarizing reflector 24. In other words, the transmission axis of the polarizing plate 25 is aligned with the Y direction in a plan view and is parallel to the second polarization direction of the second linearly polarized light PL2. The +Z side surface of the polarizing plate 25 corresponds to the display surface 20a.

[0030] The liquid crystal layer 23, the polarizing reflector 24, and the polarizing plate 25 overlap with the effective region AA in a plan view. Note that in Figure 5, only the main parts of the liquid crystal display panel 20 are shown in a simplified manner, and the liquid crystal display panel 20 further comprises components not shown. For example, the second substrate 22 further comprises a light-shielding layer, a color filter layer, an overcoat layer, spacers, etc. The first substrate 21 further comprises multiple scan lines, multiple signal lines, switching elements electrically connected to each pixel electrode PE, various insulating films, etc.

[0031] The reflector 30 shown in Figures 1 and 2 reflects the second linearly polarized light PL2 reflected by the polarizing reflector 24 toward the liquid crystal display panel 20. The reflector 30 is rectangular in shape with sides extending along the Y direction in a plan view. The reflector 30 is parallel to the liquid crystal display panel 20.

[0032] Figure 6 is a cross-sectional view of the reflector 30. The reflector 30 comprises a first plate portion 31 and a second plate portion 32.

[0033] The first plate portion 31 is incident on the second linearly polarized light PL2 reflected by the polarizing reflector 24. The first plate portion 31 imparts a phase difference of 1 / 4 wavelength to the incident light. The first plate portion 31 is a 1 / 4 phase difference plate.

[0034] Figure 7 shows the reflector 30 as viewed along a direction perpendicular to the plate surface of the reflector 30. The first plate portion 31 has a leading axis FA and a lagging axis DA that are inclined at 45° with respect to the second polarization direction of the second linearly polarized light PL2 along the Y direction.

[0035] The second plate portion 32 shown in Figure 6 reflects light transmitted through the first plate portion 31 toward the liquid crystal display panel 20 via the first plate portion 31. The +Z side surface of the second plate portion 32 that reflects light (corresponding to the "reflective surface"; hereinafter referred to as the second reflective surface 32a) is, for example, a mirror surface. The light reflectivity of the second reflective surface 32a is 80% or more. The first plate portion 31 is bonded to the second reflective surface 32a, for example, via a light-transmitting adhesive layer.

[0036] Furthermore, the thickness of the first plate portion 31 and the thickness of the adhesive layer are sufficiently small compared to the thickness of the reflector 30. For example, the thickness of the first plate portion 31 is 8 μm. Therefore, the thickness of the first plate portion 31 can be ignored in the reflector 30. Consequently, the second reflective surface 32a can be considered as the +Z side surface (front surface) of the reflector 30.

[0037] Figure 8 is a schematic cross-sectional view of the display device 1 showing the positional relationship between the light source device 10, the liquid crystal display panel 20, and the reflector 30. Note that in Figure 8, only the first reflective surface 24a of the polarizing reflector 24 of the liquid crystal display panel 20 is shown. In Figure 8, only the second reflective surface 32a of the reflector 30 is shown.

[0038] Furthermore, Figures 1, 2, 3, and 8 show the first virtual plane VS1, the second virtual plane VS2, and the third virtual plane VS3, which are illustrated by dashed lines. In Figure 1, the portions of the first virtual plane VS1, the second virtual plane VS2, and the third virtual plane VS3 that overlap with the dashed lines representing the effective area AA, the light source device 10, and the reflector 30 are shown with dashed lines. As will be described later, the reflector 30 is located between the liquid crystal display panel 20 and the light source device 10 in the Z direction, and in Figure 1, only the reflector 30 is shown in the portion where the reflector 30 and the light source device 10 overlap.

[0039] The first virtual plane VS1 is a virtual plane that is perpendicular to the Y direction and passes through the -Y side edge of the effective region AA. The first point P1 shown in Figure 2.8 indicates the position where the first reflection surface 24a and the first virtual plane VS1 intersect. The second virtual plane VS2 is a virtual plane that is perpendicular to the Y direction and passes through the +Y side edge of the effective region AA. The second point P2 indicates the position where the first reflection surface 24a and the second virtual plane VS2 intersect.

[0040] The third virtual plane VS3 is a virtual plane that is perpendicular to the Y direction and passes through the -Y side edge of the second reflective surface 32a. The third point P3 is located on the -Y side edge of the second reflective surface 32a. The third virtual plane VS3 lies between the first virtual plane VS1 and the second virtual plane VS2. In this embodiment, the third virtual plane VS3 equally divides the effective region AA in the Y direction. The fourth point P4 is the point where the third virtual plane VS3 and the first reflective surface 24a intersect. In this embodiment, the fourth point P4 corresponds to the midpoint of the first point P1 and the second point P2.

[0041] When the display device 1 is viewed along the direction in which the optical axis of the emitted light SL extends (Z direction), the light source device 10 and the reflector 30 overlap with the liquid crystal display panel 20. When the display device 1 is viewed along the Z direction, there is no gap between the light source device 10 and the reflector 30. In other words, the effective area AA overlaps with either the light source device 10 or the reflector 30 in a plan view. Specifically, in a plan view, the area between the first virtual plane VS1 and the third virtual plane VS3 in the effective area AA overlaps with the light source device 10. Also, in a plan view, the area between the third virtual plane VS3 and the second virtual plane VS2 in the effective area AA overlaps with the reflector 30.

[0042] Furthermore, the reflector 30 is positioned between the liquid crystal display panel 20 and the light source device 10 in the direction (Z direction) in which the optical axis of the emitted light SL extends. The distance between the reflector 30 and the liquid crystal display panel 20 shown in Figure 8 is determined by the distance at which the light reflected by the reflector 30 (second reflective surface 32a) toward the liquid crystal display panel 20 enters the range between the third virtual surface VS3 and the second virtual surface VS2 on the polarizing reflector 24 (first reflective surface 24a). In this embodiment, the distance between the reflector 30 and the liquid crystal display panel 20 is determined to satisfy the following equation (1).

[0043] d = V / (4 × tanθ) ... (1)

[0044] In equation (1), d is the distance between the reflector 30 and the liquid crystal display panel 20, V is the length of the effective region AA along the second direction D2 (the length between the first point P1 and the second point P2), and θ is the inclination angle.

[0045] Figure 2.8 further shows the first auxiliary line HL1, the second auxiliary line HL2, the third auxiliary line HL3, and the fifth point P5. The first auxiliary line HL1 is a virtual line passing through the first point P1 and along the first direction D1. The second auxiliary line HL2 is a virtual line passing through the first point P1 and the third point P3. The third auxiliary line HL3 is a virtual line passing through the third point P3 and along the first direction D1. The fifth point P5 indicates the intersection of the first reflective surface 24a and the third auxiliary line HL3.

[0046] In Figure 8, the angles between the first virtual plane VS1 and the first auxiliary line HL1, the angles between the first auxiliary line HL1 and the second auxiliary line HL2, the angles between the second auxiliary line HL2 and the third auxiliary line HL3, and the angles between the third auxiliary line HL3 and the third virtual plane VS3 all correspond to the inclination angle θ. Also, the length between the fourth point P4 and the first point P1 corresponds to V / 2, and the length between the fourth point P4 and the fifth point P5 corresponds to V / 4. Furthermore, the distance between the reflector 30 and the liquid crystal display panel 20 corresponds to the length between the fifth point P5 and the third point P3.

[0047] In other words, the distance (d) between the reflector 30 and the liquid crystal display panel 20 is calculated from the angle (θ) between the third auxiliary line HL3 and the third virtual plane VS3, and the length (4 / V) between the fourth point P4 and the fifth point P5, as shown in equation (1).

[0048] Next, we will explain the operation of the display device 1 when it displays an image.

[0049] First, the light source device 10 emits light SL toward the liquid crystal display panel 20. The light source device 10 emits light SL from a region that includes the area between the first virtual plane VS1 and the third virtual plane VS3 in a planar view.

[0050] The emitted light SL travels along the Z direction and enters the region on the -Y side from the third virtual plane VS3 at the polarizing reflector 24. The polarizing reflector 24 transmits the first linearly polarized light PL1 contained in the emitted light SL.

[0051] Furthermore, the polarizing reflector 24 reflects the second linearly polarized light PL2 contained in the emitted light SL. The second linearly polarized light PL2 reflected by the polarizing reflector 24 (hereinafter referred to as the first reflected light RL1) travels along the second auxiliary line HL2 and is incident on the reflector 30. The first reflected light RL1 is linearly polarized along the second polarization direction. In other words, the first reflected light RL1 is P-polarized.

[0052] As shown in Figure 8, the first reflected light RL1 reflected at the first point P1 on the first reflective surface 24a travels toward the third point P3 on the second reflective surface 32a. Similarly, the first reflected light RL1 reflected at the fourth point P4 on the first reflective surface 24a travels toward the sixth point P6 on the second reflective surface 32a. The sixth point P6 is the point where the second reflective surface 32a intersects with the fourth auxiliary line HL4, which passes through the fourth point P4 and is parallel to the second auxiliary line HL2. Furthermore, the sixth point P6 corresponds to the point where the second reflective surface 32a intersects with the second virtual surface VS2.

[0053] In the reflector 30, the first reflected light RL1 passes through the first plate portion 31. The first reflected light RL1 that has passed through the first plate portion 31 is reflected by the second reflective surface 32a with a phase difference of 1 / 4 wavelength. Hereinafter, the first reflected light RL1 reflected by the second reflective surface 32a will be referred to as the second reflected light RL2. The second reflected light RL2 travels along the Z direction and passes through the first plate portion 31. The second reflected light RL2 that has passed through the first plate portion 31 is given a phase difference of 1 / 4 wavelength. In other words, the second reflected light RL2 that has passed through the first plate portion 31 has a phase difference of 1 / 2 wavelength with respect to the first reflected light RL1 (second polarization direction: P polarization). Therefore, the second reflected light RL2 that has passed through the first plate portion 31 is linearly polarized along the first polarization direction which is perpendicular to the second polarization direction. That is, the second reflected light RL2 is S-polarized.

[0054] The second reflected light RL2 that has passed through the first plate portion 31 is incident on the polarizing reflector 24. As shown in Figure 8, the second reflected light RL2 reflected at the third point P3 of the second reflective surface 32a travels toward the fourth point P4 of the first reflective surface 24a. Also, the second reflected light RL2 reflected at the sixth point P6 of the second reflective surface 32a travels toward the second point P2 of the first reflective surface 24a.

[0055] As described above, the polarizing reflector 24 has a transmission axis aligned with the first polarization direction. In other words, the polarizing reflector 24 transmits the second reflected light RL2 (S-polarized) in the region between the second virtual plane VS2 and the third virtual plane VS3. Also, as described above, the polarizing reflector 24 transmits the first linearly polarized light PL1 (S-polarized) in the region between the first virtual plane VS1 and the third virtual plane VS3.

[0056] Therefore, the polarizing reflector 24 transmits light (S-polarized light) along the first polarization direction in the region between the first virtual plane VS1 and the second virtual plane VS2 (i.e., the region that overlaps with the effective region AA in a plan view). As a result, light (S-polarized light) along the first polarization direction is incident on the liquid crystal display panel 20.

[0057] In the liquid crystal display panel 20, a voltage is applied to the pixel electrode PE and the common electrode CE based on an image signal transmitted from an external device, generating an electric field in the liquid crystal layer 23 and changing the orientation of the liquid crystal molecules LM. As a result, the light transmitted through the liquid crystal display panel 20 is modulated, and an image is displayed on the display surface 20a.

[0058] Next, we will compare the display device 1 of this embodiment with a comparative example display device that does not have a reflector 30.

[0059] In the comparative example display device that does not have a reflector 30, the light source device 10 needs to emit light SL into the entire effective area AA in a plan view. In this case, the light source device 10 overlaps with the entire effective area AA in a plan view.

[0060] On the other hand, in the display device 1 of this embodiment, the light source device 10 should be positioned so as to overlap with the area between the first virtual surface VS1 and the third virtual surface VS3 of the effective area AA in a plan view. In other words, in the display device 1 of this embodiment, the size of the light source device 10 can be reduced to approximately half that of the display device of the comparative example. Therefore, the display device 1 can reduce power consumption.

[0061] Furthermore, if the light source device 10 is equipped with a heat dissipation member (a so-called heat sink) that releases heat from the light-emitting body 12, the power consumption can be reduced as described above, thereby allowing the size of the heat dissipation member to be reduced.

[0062] Furthermore, as described above, the reflector 30 is positioned between the liquid crystal display panel 20 and the light source device 10 in the direction in which the optical axis of the emitted light SL extends. Moreover, when viewing the display device 1 along the direction in which the optical axis of the emitted light SL extends, the light source device 10 and the reflector 30 overlap with the liquid crystal display panel 20. Therefore, the size of the display device 1 in this embodiment is approximately the same as the size of the display device 1 without the reflector 30. In other words, the display device 1 in this embodiment can suppress power consumption without increasing the size of the display device 1.

[0063] <Head-Up Display 2> Figure 9 is a schematic diagram of a head-up display 2 according to an embodiment of the present disclosure. The X, Y, and Z directions shown in Figure 9 are the same as the X, Y, and Z directions shown in Figure 1.

[0064] The head-up display 2 (hereinafter referred to as HUD2) projects an image onto a translucent material 3, allowing the user U to view a virtual image VG. The translucent material 3 is, for example, the windshield, but it goes without saying that it is not limited to the windshield; any configuration on which the image of the HUD2 is projected is acceptable.

[0065] The HUD2 comprises a housing 40, a display device 1, and an optical element 50. The housing 40 houses the display device 1 and the optical element 50.

[0066] Display device 1 is the display device 1 described above. The light FL emitted from display device 1 is directed towards the optical member 50 along the Z direction.

[0067] The optical element 50 guides the light FL emitted from the display device 1 to the light-transmitting body 3 through the opening 40a of the housing 40. Specifically, the optical element 50 is a concave mirror. The optical element 50 may be composed of multiple concave mirrors and reflecting mirrors.

[0068] The light FL guided by the optical component 50 is projected onto the translucent body 3. User U, who directs their gaze towards the light FL projected onto the translucent body 3, sees the virtual image VG.

[0069] In the display device 1 of the HUD2, power consumption can also be suppressed as described above. In the HUD2, the amount of light from the light source 10 is increased compared to when the user U directly views the display surface 20a of the display device 1, in order to allow the user U to see the virtual image VG. Therefore, power consumption can be efficiently suppressed in the HUD2.

[0070] <Variation> While preferred embodiments of this disclosure have been described above, this disclosure is not limited to such embodiments. The content disclosed in the embodiments is merely an example, and various modifications are possible without departing from the spirit of this disclosure. Any modifications made without departing from the spirit of this disclosure will naturally fall within the technical scope of this disclosure.

[0071] For example, the first linearly polarized light PL1 may be P-polarized. In this case, the first polarization direction of the first linearly polarized light PL1 is aligned with the Y direction. Also in this case, the second linearly polarized light PL2 is S-polarized, and the second polarization direction of the second linearly polarized light PL2 is aligned with the X direction. Furthermore, in this case, the transmission axis of the polarizing reflector 24 is aligned with the first polarization direction (Y direction), and the transmission axis of the polarizer 25 is aligned with the second polarization direction (X direction). Also in this case, the virtual axis line VA shown in Figure 2 is aligned with the second polarization direction (X direction) of the second linearly polarized light PL2. In other words, in this case, the liquid crystal display panel 20 is tilted around the virtual axis line VA which is aligned with the second polarization direction of the second linearly polarized light PL2.

[0072] Furthermore, the third virtual plane VS13 of the modified example, shown by the dashed line in Figure 8, is located closer to the second virtual plane VS2 than the third virtual plane VS3 of the above embodiment. In this case, the second reflective surface 132a (reflector 130) of the modified example, shown by the dashed line, is shorter than the second reflective surface 32a of the above embodiment, and the light source device 110 of the modified example, shown by the dashed line, is larger than the light source device 10 of the above embodiment. Also in this case, the reflector 130 of the modified example may be closer to the liquid crystal display panel 20 than the reflector 30 of the above embodiment. Even in this case, the second reflected light RL2 is incident on the region between the third virtual plane VS3 and the second virtual plane VS2 of the polarizing reflector 24.

[0073] Therefore, based on the display device 1 of the above embodiment and the display device 1 of the modified example, the distance (d) between the reflector 30 and the liquid crystal display panel 20 may be determined to satisfy the following equation (2).

[0074] d ≤ V / (4 × tanθ) ... (2)

[0075] On the other hand, if the reflector 30 is further away from the liquid crystal display panel 20 than the reflector 30 in the above embodiment, the first reflected light RL1 reflected at the first point P1 of the first reflective surface 24a is incident on the +Y side of the third point P3 of the second reflective surface 32a. In other words, in this case, a region is created at the -Y side end of the second reflective surface 32a where the first reflected light RL1 is not incident. As a result, a region is created in the polarizing reflector 24 between the third virtual surface VS3 and the second virtual surface VS2 where the second reflected light RL2 is not incident. Therefore, the image is not properly displayed on the display surface 20a. In other words, the distance (d) between the reflector 30 and the liquid crystal display panel 20 must satisfy the above equation (2).

[0076] Furthermore, the reflector 30 does not have to be parallel to the liquid crystal display panel 20. In this case, the liquid crystal display panel 20 may be a two-viewpoint display that displays a first image in the direction in which the emitted light SL travels (Z direction) and a second image in the direction in which the second reflected light RL2 travels.

[0077] Furthermore, any other effects and advantages brought about by the embodiments described herein that are obvious from the description herein or that can be appropriately conceived by a person skilled in the art are naturally provided by this disclosure. [Explanation of Symbols]

[0078] 1 Display device 2 Head-Up Display 10 Light source device 20 LCD display panels 20a Display surface 21 First board 22 Second board 23 Liquid crystal layer 24 Polarizing reflector 24a 1st reflective surface 25 Polarizing plates 30 Reflector 31 1st plate part 32 2nd plate part 32a 2nd reflective surface (reflective surface) PL1 1st linear polarization PL2 2nd linear polarization SL output light VA virtual axis

Claims

1. A light source device that emits light including a first linearly polarized light and a second linearly polarized light orthogonal to the first linearly polarized light, A liquid crystal display panel having a polarizing reflector that receives the emitted light, transmits the first linearly polarized light, and reflects the second linearly polarized light, and which is tilted with respect to the optical axis of the emitted light, The system comprises a reflector that reflects the second linearly polarized light reflected by the polarizing reflector toward the liquid crystal display panel, The aforementioned reflector is The polarizing reflector reflects the second linearly polarized light, which is incident upon the first plate portion that gives the incident light a phase difference of 1 / 4 wavelength, The device comprises a second plate portion that reflects light transmitted through the first plate portion toward the liquid crystal display panel via the first plate portion, Display device.

2. The reflector is parallel to the liquid crystal display panel. The display device according to claim 1.

3. The liquid crystal display panel is tilted around a virtual axis that is aligned with one of the polarization directions of the first linear polarization and the second linear polarization. The display device according to claim 1.

4. The reflector is positioned between the liquid crystal display panel and the light source device in the direction in which the optical axis of the emitted light extends. The display device according to claim 1.

5. When viewed along the direction in which the optical axis of the emitted light extends, the light source device and the reflector overlap with the liquid crystal display panel. The display device according to claim 1.

6. The aforementioned liquid crystal display panel is A first substrate on which the polarizing reflector is arranged, A second substrate facing the first substrate on the opposite side of the polarizing reflector, A liquid crystal layer disposed between the first substrate and the second substrate, The system comprises a polarizing plate disposed on the second substrate opposite the liquid crystal layer and having a transmission axis parallel to the polarization direction of the second linearly polarized light, The display device according to claim 1.

7. A light source device that emits light including a first linearly polarized light and a second linearly polarized light orthogonal to the first linearly polarized light, A liquid crystal display panel having a polarizing reflector that receives the emitted light, transmits the first linearly polarized light, and reflects the second linearly polarized light, and which is tilted with respect to the optical axis of the emitted light, The system comprises a reflector that reflects the second linearly polarized light reflected by the polarizing reflector toward the liquid crystal display panel, The aforementioned reflector is The polarizing reflector receives the second linearly polarized light, which is incident on the first plate portion and gives the second linearly polarized light a phase difference of 1 / 4 wavelength, The device comprises a second plate portion that reflects light transmitted through the first plate portion toward the liquid crystal display panel via the first plate portion, Head-up display.

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