WO2015122491A1

WO2015122491A1 - Head-up display device

Info

Publication number: WO2015122491A1
Application number: PCT/JP2015/053966
Authority: WO
Inventors: 代工　康宏; 中村　やよい
Original assignee: 株式会社オルタステクノロジー
Priority date: 2014-02-13
Filing date: 2015-02-13
Publication date: 2015-08-20
Also published as: JP6247952B2; JP2015152732A

Abstract

A head-up display device (10) includes the following: a light source unit (11); a liquid crystal display element (12) that has a first polarizing plate (41) provided on the light source unit (11) side, and a second polarizing plate (43) disposed opposite the first polarizing plate (41) with a liquid crystal layer (32) therebetween; and a reflection-type polarizing plate (13) that is disposed opposite the second polarizing plate (43) and that reflects light components which are parallel to a reflection axis. A display surface of the liquid crystal display element (12) is substantially parallel to a light emission surface of the light source unit (11), and the reflection-type polarizing plate (13) is inclined towards the display surface of the liquid crystal display element (12).

Description

Head-up display device

The present invention relates to a head-up display device, and more particularly to a head-up display device using a liquid crystal display element.

A head-up display (HUD) device is known which projects display light from a liquid crystal display element on a windshield of a vehicle or the like to display a virtual image (display image). In this head-up display device, for example, display light obtained by illumination light from a backlight transmitted through a liquid crystal display element is reflected by a reflecting mirror (or a concave mirror), and the reflected light is projected on a display member such as a windshield or a combiner. Thus, the driver visually recognizes the virtual image displayed on the display member. This allows the driver to read information with little movement of the visual field from the driving state.

In the head-up display device, due to its structure, a part of external light (external light) such as sunlight (in particular, a light component parallel to the light path of the backlight and in the opposite direction) is liquid crystal used in the head-up display device The display element may be irradiated. In this case, due to the external light reflected by the display surface of the liquid crystal display element, an unnecessary image which should not be displayed is projected on the windshield. This degrades the display characteristics of the liquid crystal display element.

JP, 2011-247997, A

The present invention provides a head-up display device capable of suppressing deterioration in contrast of a liquid crystal display element and suppressing deterioration of display characteristics due to external light.

A head-up display device according to an aspect of the present invention includes a light source unit, a first polarizing plate provided on the light source unit side, and a second polarizing plate disposed opposite to the first polarizing plate via a liquid crystal layer. And a reflective polarizing plate disposed opposite to the second polarizing plate and reflecting a light component parallel to the reflection axis. The display surface of the liquid crystal display element may be substantially parallel to the light emission surface of the light source unit, and the reflective polarizer may be inclined with respect to the display surface of the liquid crystal display element.

In the head-up display device according to one aspect of the present invention, a light source unit, a first polarizing plate provided on the light source unit side, and a second polarizing plate disposed opposite to the first polarizing plate via a liquid crystal layer. A liquid crystal display element having a polarizing plate, a reflective polarizing plate disposed opposite to the second polarizing plate and reflecting a light component parallel to the reflection axis, a distance between the liquid crystal display element and the reflective polarizing plate And a spacer having a refractive index substantially the same as the reflective polarizing plate. The display surface of the liquid crystal display element is substantially parallel to the light emission surface of the light source unit and is inclined with respect to a plane perpendicular to the light path of the external light, and the reflective polarizing plate is the one of the liquid crystal display element. It is characterized in that it is inclined with respect to the display surface.

ADVANTAGE OF THE INVENTION According to this invention, while suppressing that the contrast of a liquid crystal display element falls, it can provide the head-up display apparatus which can suppress that a display characteristic degrades due to external light.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing of the head-up display apparatus which concerns on 1st Embodiment of this invention. FIG. 2 is a cross-sectional view of the liquid crystal display element and the reflective polarizing plate shown in FIG. Sectional drawing which shows the more specific structural example of a liquid crystal display element. Sectional drawing of the head-up display apparatus for demonstrating the optical path of external light. Sectional drawing of the liquid crystal display element for demonstrating the optical path of exterior light, and a reflection type polarizing plate. Sectional drawing of the liquid crystal display element which concerns on 2nd Embodiment of this invention, and a reflection type polarizing plate. Sectional drawing of the head-up display apparatus which concerns on 3rd Embodiment of this invention. Sectional drawing of the liquid crystal display element and reflection type polarizing plate which were shown in FIG. Sectional drawing of the head-up display apparatus for demonstrating the optical path of external light. Sectional drawing of the liquid crystal display element for demonstrating the optical path of exterior light, and a reflection type polarizing plate.

Hereinafter, embodiments will be described with reference to the drawings. However, it should be noted that the drawings are schematic or conceptual, and the dimensions and proportions of the drawings are not necessarily the same as the actual ones. Further, even when the same part is shown in the drawings, the dimensional relationships and ratios may be expressed differently. In particular, some embodiments described below illustrate apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention depends on the shape, structure, arrangement, etc. of components. Is not to be identified. In the following description, elements having the same function and configuration are given the same reference numerals, and redundant description will be made only when necessary.

First Embodiment
[1. Configuration of Head-up Display Device 10]
FIG. 1 is a cross-sectional view of a head-up display device 10 according to a first embodiment of the present invention. The head-up display device 10 includes a light source unit 11, a liquid crystal display element 12, a reflective polarizing plate 13, a reflecting mirror 14, a case 15, and a display member 16.

The light source unit 11 includes, for example, a light source (surface light source) having a surface shape, and supplies illumination light to the liquid crystal display element 12. The light source unit 11 includes a substrate 20, a light emitting element 21, a heat sink (heat absorbing plate) 22, a support member 23, a light source optical system 24, and a support member (lens holder) 25. One or more light emitting elements 21 are provided on the substrate 20. As the light emitting element 21, for example, a white light emitting diode (LED: Light Emitting Diode) is used. The substrate 20 is formed of a circuit board provided with a wiring for supplying power to the light emitting element 21. A heat sink 22 for absorbing or radiating the heat of the light source unit 11 is provided on the bottom surface of the substrate 20.

A light source optical system 24 is provided above the substrate 20. The light source optical system 24 includes, for example, a plano-convex lens L1 and a convex lens (biconvex lens) L2. The plano-convex lens L1 is supported by a support member 23 provided on the substrate 20, and the convex lens L2 is supported by a support member 25 provided on the heat sink 22. The light source optical system 24 condenses the illumination light from the light emitting element 21 and emits it in a certain direction. The illumination light emitted from the light source optical system 24 to the liquid crystal display element 12 side becomes a surface light source.

A liquid crystal display element 12 and a reflective polarizing plate 13 are provided on the light path of the light source unit 11. The liquid crystal display element 12 and the reflective polarizing plate 13 are supported by a support member 15 b provided in the case 15. The liquid crystal display element 12 transmits illumination light from the light source unit 11 to perform light modulation. And the liquid crystal display element 12 displays the image which shows driving | operation information, such as a vehicle speed.

The reflecting mirror (reflecting member) 14 is configured of a plane mirror, a concave mirror or the like. The reflecting mirror 14 reflects the display light from the liquid crystal display element 12 toward the display member 16. When a concave mirror is used as the reflecting mirror 14, the concave mirror can magnify the display light from the liquid crystal display element 12 at a predetermined magnification.

The display member 16 is used to project display light from the liquid crystal display element 12 and reflects the display light to the driver 17 to display the display light as a virtual image 18. Examples of information visually recognized by the driver 17 as the virtual image 18 include the vehicle speed, the engine rotation speed, the traveling distance, the navigation information, the outside air temperature, and the like.

The display member 16 is, for example, a windshield of a vehicle. The display member 16 may be a translucent screen (combiner) provided exclusively for the head-up display device 10. The combiner is used, for example, mounted on a dashboard of a vehicle, mounted on a rearview mirror arranged in front of the driver 17, or mounted on a sun visor installed on the top of a windshield. The combiner is made of, for example, a plate-like synthetic resin base material having a curved surface, and a vapor deposition film made of titanium oxide, silicon oxide or the like is applied to the surface of the base material. Prepare.

The case 15 accommodates the light source unit 11, the liquid crystal display element 12, the reflective polarizing plate 13, and the reflecting mirror 14. The case 15 includes an opening 15 a through which display light reflected by the reflecting mirror 14 passes. A translucent member may be used instead of the opening 15a. The case 15 is housed, for example, in a dashboard.

FIG. 2 is a cross-sectional view of the liquid crystal display element 12 and the reflective polarizing plate 13 shown in FIG. The liquid crystal display element 12 includes a pair of

substrates

30 and 31, a liquid crystal layer 32, a sealing material 33 for sealing the liquid crystal layer 32 between the substrate 30 and the substrate 31, and a pair of retardation plates (λ / 4

plates

40, 42 and a pair of

polarizing plates

41, 43.

FIG. 3 is a cross-sectional view showing a more specific configuration example of the liquid crystal display element 12.
The liquid crystal display element 12 includes a TFT substrate 30 on which switching elements and pixel electrodes are formed, a color filter substrate (CF substrate) 31 on which a color filter, a common electrode and the like are formed and which is disposed opposite to the TFT substrate 30 The liquid crystal layer 32 sandwiched between the substrate 30 and the CF substrate 31 is provided. Each of the TFT substrate 30 and the CF substrate 31 is formed of a transparent substrate (for example, a glass substrate). The CF substrate 31 is disposed on the light source unit 11 side, and illumination light from the light source unit 11 is incident on the liquid crystal layer 32 from the CF substrate 31 side.

The liquid crystal layer 32 is formed of a liquid crystal material sealed by a sealing material 33 which bonds the TFT substrate 30 and the CF substrate 31 to each other. In the liquid crystal material, the alignment of liquid crystal molecules is manipulated in accordance with the electric field applied between the TFT substrate 30 and the CF substrate 31, and the optical characteristics are changed. As a liquid crystal mode, for example, a VA (Vertical Alignment) mode is used, but of course, another liquid crystal mode such as a TN (Twisted Nematic) mode or a homogeneous mode may be used.

A plurality of switching elements 34 are provided on the TFT substrate 30 on the liquid crystal layer 32 side. For example, a thin film transistor (TFT: Thin Film Transistor) is used as the switching element 34. The TFT includes a gate electrode electrically connected to a scanning line (not shown), a gate insulating film provided on the gate electrode, and a semiconductor layer (for example, an amorphous silicon layer) provided on the gate insulating film. And a source electrode and a drain electrode provided separately on the semiconductor layer. The source electrode is electrically connected to a signal line (not shown).

An insulating layer 35 is provided on the switching element 34. A plurality of pixel electrodes 36 are provided on the insulating layer 35. A contact plug 37 electrically connected to the pixel electrode 36 is provided in the insulating layer 35 and on the drain electrode of the switching element 34.

A color filter 38 is provided on the CF substrate 31 on the liquid crystal layer 32 side. The color filter 38 includes a plurality of colored filters (colored members), and specifically includes a plurality of red filters 38-R, a plurality of green filters 38-G, and a plurality of blue filters 38-B. A common color filter is composed of three primary colors of light, red (R), green (G) and blue (B). Adjacent sets of three colors of R, G, and B are units of display (referred to as pixels or pixels), and a single-color portion of R, G, or B in one pixel is a sub-pixel (sub-pixel (sub-pixel This is a minimum drive unit called a pixel). The switching element 34 and the pixel electrode 36 are provided for each sub-pixel.

A black matrix (light shielding film) BM for light shielding is provided at the boundary between the red filter 38-R, the green filter 38-G, and the blue filter 38-B, and at the boundary between pixels (sub-pixels). That is, the black matrix BM is formed in a mesh shape. The black matrix BM is provided to shield unnecessary light between the coloring members and to improve the contrast.

A common electrode 39 is provided on the color filter 38 and the black matrix BM. The common electrode 39 is planarly formed on the entire display area of the liquid crystal display element 12.

A retardation plate 40 and a polarizing plate 41 are provided on the TFT substrate 30 on the light source unit 11 side. A retardation plate 42 and a polarizing plate 43 are provided on the CF substrate 31 opposite to the liquid crystal layer 32.

The

polarizing plates

41 and 43 have transmission axes and absorption axes orthogonal to each other in a plane orthogonal to the traveling direction of light. The

polarizers

41 and 43 transmit linearly polarized light (linearly polarized light component) having a vibration plane parallel to the transmission axis among light having vibration planes in random directions, and have a vibration plane parallel to the absorption axis. It absorbs linearly polarized light (linearly polarized light component). The

polarizing plates

41 and 43 are arranged such that their transmission axes are orthogonal to each other, that is, in a crossed nicol state. As shown in FIG. 2, the transmission axis of the polarizing plate 43 is set at an arbitrary angle φ with respect to the horizontal direction.

The

retardation plates

40 and 42 have refractive index anisotropy, and have slow axes and fast axes that are orthogonal to each other in a plane orthogonal to the traveling direction of light. The

retardation plates

40 and 42 have predetermined retardation (a retardation of λ / 4 when λ is a wavelength of light passing through) between light of a predetermined wavelength transmitting through the slow axis and the fast axis, respectively. It has a function to give. That is, the

phase difference plates

40 and 42 are formed of λ / 4 plates. The slow axis of the retardation plate 40 is set to form an angle of 45 ° with the transmission axis of the polarizing plate 41. The slow axis of the retardation plate 42 is set to form an angle of 45 ° with the transmission axis of the polarizing plate 43.

The pixel electrode 36, the contact plug 37, and the common electrode 39 are formed of a transparent electrode, and for example, ITO (indium tin oxide) is used. A transparent insulating material is used as the insulating layer 35, and, for example, silicon nitride (SiN) is used.

Returning to FIG. 2, the liquid crystal display element 12 is disposed such that the display surface (the surface of the substrate 30 or the substrate 31) of the liquid crystal display element 12 is substantially perpendicular to the light path of the light source unit 11. In other words, the display surface of the liquid crystal display element 12 is disposed substantially in parallel with the light emitting surface of the light source unit 11. The display surface of the liquid crystal display element 12 is a surface on which an image light-modulated by the liquid crystal display element 12 is displayed, and corresponds to the surface of the CF substrate 31 or the polarizing plate 43 in the configuration example of FIG. The display surface of the liquid crystal display element 12 is parallel to the surface (substrate surface) of the TFT substrate 30 or the CF substrate 31. When expressing the arrangement and inclination of the liquid crystal display element 12, the display surface and the substrate surface are the same. In the configuration example of FIG. 1, the light emission surface of the light source unit 11 corresponds to the main surface of the lens L2, and the light emission surface of the light source unit 11 is parallel to the surface of the substrate 20.

The reflective polarizing plate 13 is provided on the display surface side of the liquid crystal display element 12 so as to be separated from the liquid crystal display element 12. The reflective polarizing plate 13 is disposed to be inclined at an angle θ with respect to the display surface of the liquid crystal display element 12. The angle θ is set so as to reduce deterioration of display characteristics caused by the reflection of external light, and is, for example, 10 degrees or more and 40 degrees or less. The reflective polarizing plate 13 has transmission axes and reflection axes orthogonal to each other in a plane orthogonal to the traveling direction of light. The reflective polarizing plate 13 transmits linearly polarized light (linearly polarized light component) having a vibration plane parallel to the transmission axis among light having vibration planes in random directions, and has a vibration plane parallel to the reflection axis. It reflects linearly polarized light (linearly polarized light component). The transmission axis of the reflective polarizing plate 13 is set parallel to the transmission axis of the polarizing plate 43. The reflective polarizing plate 13 is, for example, a DBEF (Dual Brightness Enhancement Film) manufactured by 3M or a wire grid polarizing plate of Asahi Kasei.

[2. Operation]
Next, the operation of the head-up display device 10 configured as described above will be described.

As indicated by the arrows in FIG. 1 and FIG. 2, the illumination light emitted from the light source unit 11 is transmitted through the liquid crystal display element 12 and light modulated. The display light transmitted through the liquid crystal display element 12 is incident on the reflective polarizing plate 13. Here, the transmission axis of the reflective polarizing plate 13 is substantially parallel to the transmission axis of the polarizing plate 43 of the liquid crystal display element 12. For this reason, the display light transmitted through the liquid crystal display element 12 is transmitted through the reflective polarizing plate 13. The display light transmitted through the reflective polarizing plate 13 is reflected by the reflecting mirror 14 and projected onto the display member 16. The virtual image (display image) 18 obtained by the projection of the display light onto the display member 16 is visually recognized by the driver 17. Thereby, the driver 17 can superimpose the virtual image 18 displayed in front of the driver's seat in front of the landscape for observation.

Further, the liquid crystal display element 12 is disposed with its display surface perpendicular to the light path of the light source unit 11. Therefore, the light transmitted through the liquid crystal layer 32 is approximately perpendicular to the substrate surface. Thereby, the contrast of the liquid crystal display element 12 can be prevented from decreasing.

Next, the optical path of external light incident on the head-up display device 10 will be described. The external light is various light incident from the outside of the display member 16 (the side opposite to the side on which the liquid crystal display element 12 is disposed), and is, for example, light from the outside such as sunlight.

FIG. 4 is a cross-sectional view of the head-up display device 10 for explaining the light path of the external light. FIG. 5 is a cross-sectional view of the liquid crystal display element 12 and the reflective polarizing plate 13 for explaining the optical path of the external light.

As indicated by the arrows in FIGS. 4 and 5, the external light passes through the display member 16, is reflected by the reflecting mirror 14, and is incident on the reflective polarizing plate 13. At this time, the reflective polarizing plate 13 is disposed at an angle θ with respect to a plane perpendicular to the light path of the external light. Therefore, of the external light incident on the reflective polarizing plate 13, the light component parallel to the reflection axis has the same direction as the display light of the liquid crystal display element 12 (or the opposite direction to the external light incident on the reflective polarizing plate 13) And is reflected in the direction of the angle 2θ (reflected at a reflection angle θ). That is, about half of the outside light does not reach the liquid crystal display element 12. As a result, it is possible to suppress the deterioration of the display characteristics of the head-up display device 10 due to the reflected light of the outside light reflected by the display surface of the liquid crystal display element 12.

For example, when the reflective polarizing plate 13 is not provided, the light path of the external light and the display surface of the liquid crystal display element 12 are perpendicular, so the light reflected by the liquid crystal display element 12 follows the optical path opposite to the external light. , And projected onto the display member 16. For this reason, the unnecessary image which should not be displayed originally generate | occur | produces and the display quality of the display image which the driver | operator 17 visually recognizes falls.

[3. effect]
As described above in detail, in the head-up display device 10 according to the first embodiment, the light emitting surface of the light source unit 11 and the display surface of the liquid crystal display element 12 are disposed substantially in parallel. In addition, on the display surface side of the liquid crystal display element 12, a reflective polarizing plate 13 is provided apart from the liquid crystal display element 12. The reflective polarizing plate 13 is inclined at an angle θ with respect to the display surface of the liquid crystal display element 12, and the transmission axis of the reflective polarizing plate 13 is substantially parallel to the transmission axis of the polarizing plate 43 of the liquid crystal display element 12. .

Therefore, according to the first embodiment, a part of the external light incident on the reflective polarizing plate 13 (a light component parallel to the reflection axis of the reflective polarizing plate 13) is reflected in the direction of the angle 2θ. Thereby, it can suppress that the display characteristic of the head-up display apparatus 10 deteriorates due to the reflected light in which external light was reflected by the display surface of the liquid crystal display element 12. FIG.

Further, the light emission surface of the light source unit 11 and the display surface of the liquid crystal display element 12 are disposed substantially in parallel. Therefore, the light transmitted through the liquid crystal layer 32 is approximately perpendicular to the substrate surface. Thereby, it is possible to suppress the decrease in the contrast of the liquid crystal display element 12. In the embodiment examined by the inventor, when the illumination light from the light source unit 11 is perpendicularly incident on the liquid crystal display element 12, that is, when the light in the direction perpendicular to the substrate surface is transmitted through the liquid crystal layer 32, the contrast is about 1325 is there. As the incident angle increases, the contrast decreases. For example, when the incident angle is about 22 degrees, the contrast decreases to about 183 and the contrast decreases by about 86% as compared to the vertical incidence. Therefore, by adopting the configuration of the first embodiment, it is possible to suppress the decrease in contrast.

Second Embodiment
FIG. 6 is a cross-sectional view of a liquid crystal display element 12 and a reflective polarizing plate 13 according to a second embodiment of the present invention. The configuration other than FIG. 6 is the same as that of the first embodiment.

The liquid crystal display element 12 includes an antireflective film 44 provided to face the reflective polarizing plate 13. That is, the antireflective film 44 is provided on the surface of the polarizing plate 43 facing the reflective polarizing plate 13. The anti-reflection film (AR (Anti-Reflection) film) 44 reduces reflection by, for example, light interference.

As shown in FIG. 6, of the external light incident on the reflective polarizing plate 13, a light component parallel to the transmission axis of the reflective polarizing plate 13 passes through the reflective polarizing plate 13 and reaches the liquid crystal display element 12. . The antireflective film 44 reduces reflection of external light transmitted through the reflective polarizing plate 13. Thereby, since the light component reflected by the display surface of the liquid crystal display element 12 can be reduced, it can suppress that the display quality of the display image which the driver | operator 17 visually recognizes falls.

Third Embodiment
In the third embodiment, with the light emitting surface of the light source unit 11 and the display surface of the liquid crystal display element 12 disposed substantially in parallel, both the display surface of the liquid crystal display element 12 and the reflective polarizing plate 13 are external light Be inclined to a plane perpendicular to the light path. By configuring the head-up display device 10 in this manner, the same effect as that of the first embodiment is obtained.

FIG. 7 is a cross-sectional view of a head-up display device 10 according to a third embodiment of the present invention. FIG. 8 is a cross-sectional view of the liquid crystal display element 12 and the reflective polarizing plate 13 shown in FIG.

The liquid crystal display element 12 is disposed such that the display surface of the liquid crystal display element 12 is substantially perpendicular to the light path of the light source unit 11. In other words, the display surface of the liquid crystal display element 12 is disposed substantially in parallel with the light emitting surface of the light source unit 11.

The display surface of the liquid crystal display element 12 and the light emission surface of the light source unit 11 are inclined at an angle α with respect to a plane perpendicular to the light path of the external light. A reflective polarizing plate 13 is provided on the display surface side of the liquid crystal display element 12. The reflective polarizing plate 13 is arranged to be inclined at an angle β with respect to the display surface of the liquid crystal display element 12.

A spacer 45 is provided between the liquid crystal display element 12 and the reflective polarizing plate 13 so as to fill the gap therebetween. The spacer 45 is in contact with the liquid crystal display element 12 (specifically, the polarizing plate 43) and the reflective polarizing plate 13. That is, the liquid crystal display element 12, the spacer 45, and the reflective polarizing plate 13 are integrally formed. The shape of the spacer 45 is, for example, a triangular prism. The spacer 45 is made of a material having substantially the same refractive index as the polarizing plate 43 and the reflective polarizing plate 13. The spacer 45 is made of a translucent synthetic resin material, for example, an acrylic resin. The polarizing plate 43 and the reflective polarizing plate 13 are made of, for example, a translucent synthetic resin material.

(Operation)
Next, the operation of the head-up display device 10 configured as described above will be described.

As indicated by the arrows in FIG. 7 and FIG. 8, the illumination light emitted from the light source unit 11 passes through the liquid crystal display element 12 and is light modulated. The display light transmitted through the liquid crystal display element 12 is incident on the reflective polarizing plate 13. The transmission axis of the reflective polarizing plate 13 is parallel to the transmission axis of the polarizing plate 43 of the liquid crystal display element 12. For this reason, the display light transmitted through the liquid crystal display element 12 is transmitted through the reflective polarizing plate 13.

Here, the display light transmitted through the reflective polarizing plate 13 is refracted at the interface between the reflective polarizing plate 13 and the air layer. The incident angle β and the refraction angle (α + β) of the display light are obtained. Assuming that the refractive index n of the reflective polarizing plate 13 and the refractive index of air = 1, the following relational expression is obtained from Snell's law.
sin (α + β) = n · sin β (1)
The angle α, the angle β, and the refractive index n are set such that the left side and the right side of the relational expression (1) are substantially the same. By satisfying this condition, the display light refracted at the interface of the reflective polarizing plate 13 travels in a substantially horizontal direction and enters the reflecting mirror 14. For example, when α = 10 °, β = 19 °, and n = 1.49, the display light transmitted through the reflective polarizing plate 13 travels in the horizontal direction. The angle (α + β) is set so as to reduce deterioration of display characteristics caused by the reflection of external light, and is, for example, 10 ° ≦ (α + β) ≦ 40 °. The angle α is desirably 3 ° ≦ α ≦ 15 °. Preferably, the angle β is 6 ° ≦ β ≦ 26 °.

Further, the liquid crystal display element 12 is disposed with its display surface perpendicular to the light path of the light source unit 11. Therefore, the light transmitted through the liquid crystal layer 32 is approximately perpendicular to the substrate surface. Thereby, it is possible to suppress the decrease in the contrast of the liquid crystal display element 12.

Next, the optical path of external light incident on the head-up display device 10 will be described. FIG. 9 is a cross-sectional view of the head-up display device 10 for explaining the light path of the external light. FIG. 10 is a cross-sectional view of the liquid crystal display element 12 and the reflective polarizing plate 13 for explaining the optical path of the external light.

As indicated by the arrows in FIGS. 9 and 10, the external light passes through the display member 16, is reflected by the reflecting mirror 14, and is incident on the reflective polarizing plate 13. At this time, the reflective polarizing plate 13 is disposed at an angle (α + β) with respect to a plane perpendicular to the light path of the external light. Therefore, of the external light incident on the reflective polarizing plate 13, the light component parallel to the reflection axis has the same direction as the display light of the liquid crystal display element 12 (or the opposite direction to the external light incident on the reflective polarizing plate 13) Is not reflected but reflected at a reflection angle (α + β). That is, about half of the outside light does not reach the liquid crystal display element 12. As a result, it is possible to suppress the deterioration of the display characteristics of the head-up display device 10 due to the reflected light of the outside light reflected by the display surface of the liquid crystal display element 12.

(effect)
As described above in detail, in the head-up display device 10 according to the third embodiment, the light emitting surface of the light source unit 11 and the display surface of the liquid crystal display element 12 are disposed substantially in parallel. In addition, on the display surface of the liquid crystal display element 12, a reflective polarizing plate 13 is provided via a spacer 45. The display surface of the liquid crystal display element 12 is inclined at an angle α with respect to a plane perpendicular to the light path of the external light, and the reflective polarizing plate 13 is inclined at an angle β with respect to the display surface of the liquid crystal display element 12 ing. The transmission axis of the reflective polarizing plate 13 is substantially parallel to the transmission axis of the polarizing plate 43 of the liquid crystal display element 12.

Even when the head-up display device 10 is configured as described above, the same effect as that of the first embodiment can be obtained.

The present invention is not limited to the above-described embodiment, and constituent elements can be modified and embodied without departing from the scope of the invention. Furthermore, the above embodiments include inventions of various stages, and appropriate combinations of a plurality of components disclosed in one embodiment or appropriate combinations of components disclosed in different embodiments. Various inventions can be configured. For example, even if some components are removed from all the components disclosed in the embodiment, the problem to be solved by the invention can be solved and the effects of the invention can be obtained, these components can be deleted The described embodiment can be extracted as the invention.

DESCRIPTION OF SYMBOLS 10 ... Head-up display apparatus, 11 ... Light source part, 12 ... Liquid crystal display element, 13 ... Reflection type polarizing plate, 14 ... Reflection mirror, 15 ... Case, 16 ... Display member, 17 ... Driver, 18 ... Virtual image, 20 ... Substrate 21 21 light emitting element 22 heat sink 23 support member 24 light source optical system 25 support member 30 31 substrate 32 liquid crystal layer 33 sealing material 34 switching element 35 Insulating layer, 36: pixel electrode, 37: contact plug, 38: color filter, 39: common electrode, 40, 42: retardation plate, 41, 43: polarizing plate, 44: anti-reflection film, 45: spacer.

Claims

A light source unit,
A liquid crystal display device having a first polarizing plate provided on the light source unit side, and a second polarizing plate disposed opposite to the first polarizing plate with a liquid crystal layer interposed therebetween;
A reflective polarizing plate disposed opposite to the second polarizing plate and reflecting a light component parallel to the reflection axis;
Equipped with
The display surface of the liquid crystal display element is substantially parallel to the light emission surface of the light source unit,
The head-up display device, wherein the reflective polarizing plate is inclined with respect to the display surface of the liquid crystal display element.
The head-up display device according to claim 1, wherein an inclination angle of the reflective polarizing plate is 10 degrees or more and 40 degrees or less.
The head-up display device according to claim 1, further comprising an anti-reflection film provided on the second polarizing plate.
The head-up display device according to claim 1, wherein a transmission axis of the reflective polarizing plate is substantially parallel to a transmission axis of the second polarizing plate.
A reflecting mirror that reflects display light light-modulated by the liquid crystal display element;
A display member on which the reflected light reflected by the reflecting mirror is projected;
The head-up display device according to claim 1, further comprising:
A light source unit,
A liquid crystal display device having a first polarizing plate provided on the light source unit side, and a second polarizing plate disposed opposite to the first polarizing plate with a liquid crystal layer interposed therebetween;
A reflective polarizing plate disposed opposite to the second polarizing plate and reflecting a light component parallel to the reflection axis;
A spacer provided so as to fill a gap between the liquid crystal display element and the reflective polarizing plate, and having a substantially the same refractive index as the reflective polarizing plate;
Equipped with
The display surface of the liquid crystal display element is substantially parallel to the light emission surface of the light source unit, and is inclined with respect to a plane perpendicular to the light path of the external light,
The head-up display device, wherein the reflective polarizing plate is inclined with respect to the display surface of the liquid crystal display element.
Assuming that the inclination angle α of the liquid crystal display element and the inclination angle β of the reflective polarizing plate are:
The head-up display device according to claim 6, wherein the angle (α + β) is 10 degrees or more and 40 degrees or less.
The head-up display device according to claim 6, wherein a transmission axis of the reflective polarizing plate is substantially parallel to a transmission axis of the second polarizing plate.
A reflecting mirror that reflects display light light-modulated by the liquid crystal display element;
A display member on which the reflected light reflected by the reflecting mirror is projected;
The head-up display device according to claim 6, further comprising: