Display device

Abstract

To provide a head-up display device with which it is possible to maintain high light intensity and have a viewer visually recognize a virtual image and a real image.SOLUTION: Provided is a head-up display device 1 for emitting display light L1, L2 from an opening 17 toward a windshield WS and having a virtual image VI and a real image RI visually recognized. The head-up display device comprises: a first display 12a for emitting the first display light L1 as a linearly polarized light; a second display 12b for emitting the second display light L2 as a linearly polarized light; a reflection transmission member 132 for reflecting the first display light L1 emitted from the first display 12a and entered from the front and emitting it as a linearly polarized light, and for passing the second display light L2 through that was emitted from the second display 12b and entered from the rear and emitting it as approximately circularly polarized light; and a concave mirror 14 for reflecting the first display light L1 or the second display light L2 emitted from the reflection transmission member 132 toward the windshield WS.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a head-up display device that displays a desired image to a viewer. [Background technology]

[0002] A head-up display device is known from the past, for example, as described in Patent Document 1. This head-up display device has two displays, and by transmitting the display light of one display through a half mirror and reflecting the display light of the other display through the half mirror, the optical path lengths to the windshield are made different for each display, and the driver is made to visually recognize two virtual images corresponding to the two display lights. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-039407 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional head-up display device described above, when the display light passes through and is reflected by the half mirror, the amount of light of each display light is attenuated by about half, which causes a problem in that the brightness of each display image perceived by the driver is low.

[0005] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a head-up display device that allows a viewer to view virtual and real images while maintaining high light intensity. [Means for solving the problem]

[0006] The present invention provides a head-up display device 1 having an outlet 17, which emits display light L1, L2 from the outlet 17 toward a light-transmitting member WS, thereby allowing a virtual image VI and a real image RI of a display image represented by the display light L1, L2 to be viewed. The head-up display device 1 is characterized by having a first display 12a that emits first display light L1 as linearly polarized light, a second display 12b that emits second display light L2 as linearly polarized light, a reflective / transmissive member 132 that reflects the first display light L1 emitted from the first display 12a and incident on the front surface, and emits it as linearly polarized light, and transmits the second display light L2 emitted from the second display 12b and incident on the back surface, and emits it as approximately circularly polarized light, and a concave mirror 14 that reflects the first display light L1 or the second display light L2 emitted from the reflective / transmissive member 132 toward the light-transmitting member WS. [Effects of the Invention]

[0007] According to the present invention, the first display light emitted from the first display device and the second display light emitted from the second display device can be maintained at a high light intensity, allowing a viewer to view the display images represented by each display light. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the configuration of a head-up display device according to a first embodiment of the present invention. [Figure 2] 3A and 3B are diagrams showing the results of comparing the light intensity of a virtual image and a real image in the head-up display device according to the first embodiment of the present invention with that in the case where a conventional half mirror is used. [Figure 3] FIG. 10 is a diagram showing the configuration of a head-up display device according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing the results of comparing the light intensity of a virtual image and a real image in a head-up display device according to a second embodiment of the present invention with that in a case where a conventional half mirror is used. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment of the present invention) A head-up display device (hereinafter referred to as HUD device) according to this embodiment will be described with reference to Figures 1 and 2. The HUD device according to this embodiment allows the driver to view a real image on the inside of the vehicle through the windshield, and a virtual image on the outside of the vehicle.

[0010] Fig. 1 is a diagram showing the configuration of an HUD device according to this embodiment. In Fig. 1, the HUD device 1 includes a first PGU (Picture Generation Unit) 10a having at least a first light source 11a that emits light in the visible wavelength range, for example, and a first display 12a that transmits the light emitted by the first light source 11a and emits it as linearly polarized first display light L1, thereby displaying a real image RI of a display image formed in front of the driver DR. The HUD device 1 also includes a second PGU 10b having at least a second light source 11b that emits light in the visible wavelength range, for example, and a second display 12b that transmits the light emitted by the second light source 11b and emits it as linearly polarized second display light L2, thereby displaying a virtual image VI of a display image formed in front of the driver DR.

[0011] Further, the display device includes a correction mirror 131 provided downstream of the first display 12a along the optical path of the first display light L1, which corrects distortion of the first display light L1 emitted from the first display 12a, a reflective / transmissive member 132 which reflects the first display light L1 reflected by the correction mirror 131 and incident from the front surface, and emits it as linearly polarized light, and which transmits the second display light L2 emitted from the second display 12b and incident from the back surface, and emits it as approximately circularly polarized light, a concave mirror 14 which reflects the first display light L1 or the second display light L2 emitted from the reflective / transmissive member 132 toward a windshield WS (translucent member), and a control unit 15 which controls the display content and display switching of the first display 12a and the second display 12b. The reflective / transmissive member 132 includes a ¼λ plate 132a that converts linearly polarized light into approximately circularly polarized light, and a reflective layer 132b that reflects the first display light L1 or the second display light L2. The reflective layer 132b is a first reflective layer (e.g., a cold mirror film (CMF)) that reflects linearly polarized light and transmits approximately circularly polarized light. The configuration and function of the reflective / transmissive member 132 will be described in detail later.

[0012] These components are housed in a housing 16, which is provided with an opening 17 (outlet) through which the first display light L1 and the second display light L2 are emitted, and a cover glass 18 for protecting the interior is disposed in the opening 17. The windshield WS is an example of a light-emitting member, and the opening 17 is an example of an outlet.

[0013] In Fig. 1, the first display light L1 is indicated by a dotted line, and the second display light L2 is indicated by a dashed line. In reality, countless light rays (display light) are emitted from the first display 12a and the second display 12b in Fig. 1, but here, the light rays corresponding to the upper and lower ends of the light rays emitted from the first display 12a are indicated by dotted lines of normal thickness, and the light rays of strongest light emitted from the center of the first display 12a and passing through the center of the eyebox are indicated by thick dotted lines. In addition, the light rays corresponding to the upper and lower ends of the light rays emitted from the second display 12b are indicated by dashed lines of normal thickness, and the light rays of strongest light emitted from the center of the second display 12b and passing through the center of the eyebox are indicated by thick dashed lines.

[0014] The HUD device 1 is disposed below a windshield WS of a vehicle C (for example, inside an instrument panel (hereinafter referred to as "dashboard")), and emits a first display light L1 and a second display light L2, which are projected onto the windshield WS. The first display light L1 is generated by a first light source 11a and a first display device 12a inside the HUD device 1, and the second display light L2 is generated by a second light source 11b and a second display device 12b. The first display light L1 and the second display light L2 are each emitted as linearly polarized light. The first display light L1 emitted from the first display device 12a is emitted as, for example, P-polarized linearly polarized light, and is emitted to the windshield WS through the correcting mirror 131, the reflective / transmissive member 132, and the concave mirror 14, from the opening 17 of the housing 16, and through the cover glass 18. The second display light L2 emitted from the second display device 12b is emitted as linearly polarized light, for example, P-polarized or S-polarized light, passes through the reflective / transmissive member 132, travels along the concave mirror 14, and is emitted from the opening 17 of the housing 16 through the cover glass 18 onto the windshield WS. By viewing the first display light L1 reflected by the windshield WS, the driver DR of the vehicle C can view a real image RI on the inside of the vehicle across the windshield WS, i.e., on the front side of the windshield WS as seen from the driver DR, and by viewing the second display light L2 reflected by the windshield WS, the driver DR can view a virtual image VI on the outside of the vehicle across the windshield WS, i.e., on the back side of the windshield WS as seen from the driver DR.

[0015] As the real image RI shown in FIG. 1, for example, entertainment content, assistants or agents supporting the driver DR, or characters representing them are displayed on the front side of the windshield WS as seen from the driver DR. Furthermore, as the virtual image VI, for example, vehicle information such as the speed and engine RPM of the vehicle C, route guidance displays such as turn-by-turn directions and maps, warning displays such as a speed limit exceeding warning, and other information that is highly necessary to draw the driver DR's attention are displayed. These displays provide a driving environment that reduces the need for viewpoint movement and eye focal length adjustment. The real image RI and virtual image VI include characters and icons indicating this information as well as background portions, and in a planar view from the driver DR, they have, for example, a substantially rectangular shape.

[0016] 1, the first light source 11a is, for example, a light-emitting diode (LED) that emits white light and emits light in the visible wavelength range mounted on a rigid, flat wiring board. The first display 12a is disposed closer to the opening 17 along the optical path than the first light source 11a, and has a TFT (Thin Film Transistor) first display element (not shown) that generates P-polarized first display light L1 that displays an arbitrary image in accordance with a control signal sent from the control unit 15.

[0017] Depending on the layout of the first PGU 10a, an optical axis bending member (not shown) may be disposed between the first light source 11a and the first display 12a, which receives light rays from the first light source 11a, bends the optical axis of the light rays at a predetermined angle, and outputs the light rays to the first display 12a. This optical axis bending member may be any member that can bend the optical axis of the light rays emitted from the first light source 11a, and may be, for example, a prism, a mirror, or a DFT (Direct Turning Film).

[0018] 1, the second light source 11b is, for example, a light-emitting diode that emits light in the visible wavelength range and is mounted on a rigid, flat wiring board, and emits white light. The second display 12b is provided closer to the opening 17 along the optical path than the second light source 11b, and has a TFT-type second display element (not shown) that generates P-polarized or S-polarized second display light L2 that displays an arbitrary image in accordance with a control signal sent from the control unit 15.

[0019] In addition to the above, in the first PGU 10a and the second PGU 10b, optical components such as a condenser lens, a lenticular lens, a diffusion plate, and a polarizing plate may be arranged at any position downstream of the first light source 11a and the second light source 11b, respectively.

[0020] The correcting mirror 131 and the reflecting / transmitting member 132 are mirrors that reflect the first display light L1 from the first PGU 10a, and have a mirror surface that reflects the first display light L1 and a complex free-form mirror shape in order to correct distortion of the real image RI visually recognized by the driver DR. The reflective surfaces of the correcting mirror 131 and the reflecting / transmitting member 132 are formed so that the optical focus F1 of the optical system consisting of the windshield WS, the concave mirror 14, the reflecting / transmitting member 132, and the correcting mirror 131 is located between the correcting mirror 131 and the reflecting / transmitting member 132 (closer to the opening 17 than the first display 12a). The correcting mirror 131 and the reflecting / transmitting member 132 are arranged with their angles and directions fixed without being displaced, such as rotated.

[0021] The concave mirror 14 has a mirror-like surface that reflects the first display light L1 from the first PGU 10a and the second display light L2 from the second PGU 10b toward the windshield WS. The concave mirror 14 is rotatably disposed and rotates to match the eye position of the driver DR, freely changing the emission direction of the first display light L1 and the second display light L2 to adjust the position of the image. In particular, the angle is made different when displaying a real image RI (e.g., displayed perpendicular to the road surface) and when displaying a virtual image VI (e.g., displayed at an angle to the road surface). The reflective surface of the concave mirror 14 is formed so that the optical focus F2 of the optical system consisting of the windshield WS and the concave mirror 14 is located behind the second PGU 10b (on the opposite side of the opening 17 from the second display 12b). The concave mirror 14 has a complex free-form shape to correct distortion of the virtual image VI viewed by the driver DR.

[0022] Here, the reflective / transmissive member 132 is composed of a ¼λ plate 132a and a reflective layer 132b arranged opposite the front surface of the ¼λ plate 132a, i.e., the surface on the side where the first display light L1 is incident. The ¼λ plate 132a changes the phase of the polarization of the transmitted light by ¼λ (90 degrees), converting linearly polarized light to approximately circularly polarized light and converting approximately circularly polarized light to linearly polarized light. The reflective layer 132b, which is made of a CMF, is a film that reflects linearly polarized light and transmits circularly polarized light. Note that when transmitting circularly polarized light, the CMF reflects all but a specific linearly polarized component. In other words, approximately 50% of the circularly polarized light component is reflected, and the remaining 50% is transmitted.

[0023] Here, the CMF constituting the reflective layer 132b will be described. The CMF is formed by forming a multilayer interference film with different film thicknesses on one side of a transparent substrate by a method such as vapor deposition, and reflects light in the visible wavelength range (450 to 750 nm), including the emission wavelength range, with a high reflectance (e.g., 80% or more), and reflects light outside the visible wavelength range with a low reflectance. The CMF reflects light outside the visible wavelength range, particularly light in the infrared wavelength range (infrared rays or solar heat rays), with a low reflectance (e.g., 15% or less). Light that is not reflected by the CMF is transmitted. The CMF reflects linearly polarized light and transmits approximately circularly polarized light. In this case, more than half of the linearly polarized light is reflected, and approximately half of the approximately circularly polarized light is transmitted.

[0024] The linearly polarized (e.g., P-polarized) first display light L1 emitted from the first PGU 10a and reflected by the correcting mirror 131 is incident on the front surface side of the reflective layer 132b of the reflective / transmissive member 132, and 80% or more (e.g., approximately 90%) of the first display light L1 is reflected by the concave mirror 14 as linearly polarized (P-polarized) light due to the function of the CMF. The remaining first display light L1 is transmitted through the reflective layer 132b and the ¼λ plate 132a and is absorbed by the housing 16 or the like.

[0025] That is, when only the first PGU10a is turned on, the first display light L1 is reflected by the correction mirror 131, the reflective / transmissive member 132, the concave mirror 14, and the windshield WS, and enters the eyes of the driver DR, whereby the first display light L1 is imaged in front of the windshield WS (inside the vehicle) as seen by the driver DR, and the driver DR sees the first display light L1 as a real image RI.

[0026] The second display light L2, which is linearly polarized (for example, P-polarized or S-polarized) and output from the second PGU 10b, is incident on the back surface of the ¼λ plate 132a of the reflective / transmissive member 132 and is converted into circularly polarized light by the ¼λ plate 132a. The second display light L2 converted into circularly polarized light is incident on the back surface of the reflective layer 132b and passes through the reflective layer 132b, but the P-polarized component is reflected by the function of the CMF, so that the remaining S-polarized component is converted into elliptically polarized light and output to the concave mirror 14.

[0027] That is, when only the second PGU 10b is turned on, the second display light L2 passes through the reflective / transmissive member 132, reflects off the concave mirror 14 and the windshield WS, and enters the eyes of the driver DR, whereby the second display light L2 is formed into an image on the far side of the windshield WS (outside the vehicle) as seen by the driver DR, and the driver DR sees the second display light L2 as a virtual image VI.

[0028] 2 is a diagram showing the results of comparing the light intensities of the virtual image VI and the real image RI in the HUD device 1 according to this embodiment with those in a case where a conventional half mirror is used. As shown in FIG. 2, when a half mirror is used, the first display light L1 and the second display light L2 emitted from the first PGU 10a and the second PGU 10b, respectively, are attenuated to about 50% of their light intensity and are visually recognized by the driver DR as the real image RI or the virtual image VI. On the other hand, when the reflective / transmissive member 132 composed of the ¼λ plate 132a and the reflective layer 132b made of CMF is used as in the HUD device 1 according to this embodiment, the light intensity of the second display light L2 representing the virtual image VI is attenuated to about 50%, similar to that in the case of the half mirror, but the first display light L1 representing the real image RI is attenuated to only about 90%.

[0029] As shown in FIG. 1, the light distribution of the virtual image VI is wide, while the light distribution of the real image RI is narrow, resulting in poor light efficiency. Also, as shown in FIG. 1, the virtual image VI is reflected only by the concave mirror 14 and the windshield WS, whereas the real image RI is reflected by more elements than in the case of the correcting mirror 131, the reflective / transmissive member 132, the concave mirror 14, the windshield WS, and the virtual image VI, resulting in greater attenuation and further poor light efficiency. In this configuration of the HUD device 1, as shown in FIG. 2, using the reflective / transmissive member 132 rather than a conventional half mirror keeps the light intensity of the first display light L1, which is the real image RI, high, which is extremely advantageous in terms of displaying the real image RI.

[0030] As described above, the HUD device 1 according to this embodiment includes the first display 12a that emits the first display light L1 as linearly polarized light, the second display 12b that emits the second display light L2 as linearly polarized light, the reflective / transmissive member 132 that reflects the first display light L1 emitted from the first display 12a and incident on the front surface thereof to emit the linearly polarized light, and transmits the second display light L2 emitted from the second display 12b and incident on the back surface thereof to emit the substantially circularly polarized light, and the concave mirror 14 that reflects the first display light L1 or the second display light L2 emitted from the reflective / transmissive member 132 toward the windshield WS. If necessary, the reflective / transmissive member 132 includes a ¼λ plate 132a that converts linearly polarized light into substantially circularly polarized light, and a reflective layer 132b that reflects the first display light L1 or the second display light L2. Furthermore, if necessary, the reflective layer 132b is a first reflective layer (for example, a CMF) that reflects linearly polarized light and transmits approximately circularly polarized light. Furthermore, if necessary, the reflective layer 132b is disposed in front of the ¼λ plate 132a. Furthermore, if necessary, the reflective layer 132b reflects more than half of the linearly polarized light and transmits approximately half of the approximately circularly polarized light. Furthermore, if necessary, a CMF is used as the first reflective layer.

[0031] With this configuration, the reflective / transmissive member 132 reflects linearly polarized first display light L1 from the front surface and emits it as linearly polarized light, and emits linearly polarized second display light L2 from the rear surface as approximately circularly polarized light. To achieve this function, the reflective / transmissive member 132 can be configured to include a ¼λ plate 132a that converts linearly polarized light into approximately circularly polarized light and a reflective layer 132b. The reflective layer 132b can be a first reflective layer (e.g., typically a CMF) that reflects linearly polarized light and transmits approximately circularly polarized light. This CMF transmits approximately half of the approximately circularly polarized light while reflecting linearly polarized light in the visible wavelength range with a high reflectance of 80% or more. In this case, for example, by disposing the reflective layer 132b in front of the ¼λ plate 132a, when a virtual image VI is displayed, the second display light L2 from the second display 12b is converted from linearly polarized light to circularly polarized light by the ¼λ plate 132a, passes through the CMF, becomes elliptically polarized light close to S-polarized light, and is emitted to the concave mirror 14, and the second display light L2 is emitted from the reflective-transmissive member 132 at, for example, about 50% of the brightness. On the other hand, when a real image RI is displayed, the first display light L1 from the first display 12a is reflected by the CMF as linearly polarized light, and is emitted to the concave mirror 14, and the first display light L1 can be emitted from the reflective-transmissive member 132 while maintaining a high brightness of, for example, 80% or more. In this way, particularly for real image RI, a brightness higher than that achieved when a conventional half mirror is used can be achieved.

[0032] Furthermore, if necessary, a correction mirror 131 for correcting distortion of the first display light L1 is provided between the first display 12a and the reflective / transmissive member 132 along the optical path of the first display light L1, so that distortion of the image of the real image RI as seen by the driver DR can be corrected when the real image RI is displayed.

[0033] Furthermore, if necessary, when the first display 12a emits the first display light L1, the optical focus F1 of the imaging optical system including the correcting mirror 131, the reflective / transmissive member 132, the concave mirror 14, and the window shield WS is located closer to the opening 17 than the first display 12a along the optical path of the first display light L1, and when the second display 12b emits the second display light L2, the optical focus F2 of the combined optical system including the concave mirror 14 and the window shield WS is located closer to the second light source 11b than the second display 12b along the optical path of the second display light L2.Therefore, by simply switching the display between the first display 12a and the second display 12b, the real image RI and the virtual image VI can be smoothly switched and viewed.

[0034] (Second embodiment of the present invention) The HUD device 1 according to this embodiment will be described with reference to Figures 3 and 4. In this embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0035] Fig. 3 is a diagram showing the configuration of the HUD device 1 according to this embodiment. The configuration of Fig. 3 differs from that of the HUD device 1 shown in Fig. 1 in that the reflective / transmissive member 132 includes a ¼λ plate 132a that converts linearly polarized light into approximately circularly polarized light and a reflective layer 132b that reflects the first display light L1 or the second display light L2, and the reflective layer 132b is a second reflective layer (for example, a liquid crystal polymer (LCP)) that transmits linearly polarized light and reflects approximately circularly polarized light.

[0036] 3, the reflective / transmissive member 132 includes a ¼λ plate 132a and a reflective layer 132b disposed opposite the rear surface of the ¼λ plate 132a, i.e., the surface on which the second display light L2 is incident. As described above, the ¼λ plate 132a changes the phase of the polarization of the light passing through it by ¼λ (90 degrees), converting linearly polarized light into approximately circularly polarized light and converting approximately circularly polarized light into linearly polarized light. The reflective layer 132b, made of LCP, is a liquid crystal element that reflects specific circularly polarized light and transmits circularly polarized light with a different wavelength from the specific circularly polarized light.

[0037] Here, we will explain the LCP that constitutes the reflective layer 132b. In a molten state, LCP exhibits liquid crystal-like properties, with linear chains of molecules regularly aligned. Its structure is based on parahydroxybenzoic acid. Because the melting point of a polymer of parahydroxybenzoic acid alone exceeds its thermal decomposition temperature, it is ester-bonded to various components in a linear chain to lower the melting point. While typical crystalline plastics lose their crystalline structure when melted, liquid crystal polymers maintain their crystal structure even when melted due to strong intermolecular forces, resulting in a liquid crystal state in which the molecules are regularly aligned. LCP transmits approximately 50% of linearly polarized light. It also reflects certain circularly polarized light in the same direction (e.g., clockwise circularly polarized light) and transmits circularly polarized light that is different from the specific circularly polarized light (e.g., counterclockwise circularly polarized light). LCP has a high reflectance of 80% for circularly polarized light.

[0038] The first display light L1, which is linearly polarized (for example, P-polarized) and emitted from the first PGU 10a and reflected by the correcting mirror 131, passes through the ¼λ plate 132a of the reflective / transmissive member 132 and is converted into circularly polarized light. The first display light L1 converted into circularly polarized light is reflected by the reflective layer 132b made of LCP as circularly polarized light in the same rotation direction (or is reflected and becomes circularly polarized light in the opposite rotation direction), passes through the ¼λ plate 132a again, and is output to the concave mirror 14 as linearly polarized P-polarized light.

[0039] That is, when only the first PGU10a is turned on, the first display light L1 is reflected by the correction mirror 131, the reflective / transmissive member 132, the concave mirror 14, and the windshield WS, and enters the eyes of the driver DR, whereby the first display light L1 is imaged in front of the windshield WS (inside the vehicle) as seen by the driver DR, and the driver DR sees the first display light L1 as a real image RI.

[0040] The second display light L2, which is linearly polarized (for example, P-polarized or S-polarized) and emitted from the second PGU 10b, enters the back side of the reflective layer 132b of the reflective / transmissive member 132, and approximately half of the components are transmitted due to the function of the LCP.The light then passes directly through the 1 / 4λ plate 132a, is converted into circularly polarized light, and is emitted to the concave mirror 14.

[0041] That is, when only the second PGU 10b is turned on, the second display light L2 passes through the reflective / transmissive member 132, reflects off the concave mirror 14 and the windshield WS, and enters the eyes of the driver DR, whereby the second display light L2 is formed into an image on the far side of the windshield WS (outside the vehicle) as seen by the driver DR, and the driver DR sees the second display light L2 as a virtual image VI.

[0042] 4 is a diagram showing the results of comparing the light intensities of the virtual image VI and the real image RI in the HUD device 1 according to this embodiment with those in a case where a conventional half mirror is used. As shown in FIG. 4, when a half mirror is used, the first display light L1 and the second display light L2 emitted from the first PGU 10a and the second PGU 10b, respectively, are attenuated to about 50% of their light intensity and are visually recognized by the driver DR as the real image RI or the virtual image VI. On the other hand, when the reflective / transmissive member 132 composed of the ¼λ plate 132a and the reflective layer 132b made of LCP is used as in the HUD device 1 according to this embodiment, the light intensity of the second display light L2 representing the virtual image VI is attenuated to about 50%, similar to that in the case of the half mirror, but the first display light L1 representing the real image RI is attenuated to only about 80%.

[0043] As in the case of Figure 2, by using the reflective / transmissive member 132 compared to a conventional half mirror, the light intensity of the first display light L1, which is the real image RI, can be kept high, which can be very advantageous in terms of displaying the real image RI.

[0044] As described above, the HUD device 1 according to this embodiment includes the first display 12a that emits the first display light L1 as linearly polarized light, the second display 12b that emits the second display light L2 as linearly polarized light, the reflective / transmissive member 132 that reflects the first display light L1 emitted from the first display 12a and incident on the front surface thereof to emit the linearly polarized light, and transmits the second display light L2 emitted from the second display 12b and incident on the back surface thereof to emit the substantially circularly polarized light, and the concave mirror 14 that reflects the first display light L1 or the second display light L2 emitted from the reflective / transmissive member 132 toward the windshield WS. If necessary, the reflective / transmissive member 132 includes a ¼λ plate 132a that converts linearly polarized light into substantially circularly polarized light, and a reflective layer 132b that reflects the first display light L1 or the second display light L2. Furthermore, if necessary, the reflective layer 132b is a second reflective layer (for example, LCP) that reflects linearly polarized light and transmits approximately circularly polarized light. Furthermore, if necessary, the reflective layer 132b is disposed on the back surface of the 1 / 4λ plate 132a. Furthermore, if necessary, the reflective layer 132b transmits approximately half of the linearly polarized light and reflects more than half of the approximately circularly polarized light. Furthermore, if necessary, LCP is used as the first reflective layer.

[0045] With this configuration, the reflective / transmissive member 132 reflects linearly polarized first display light L1 from the front surface and emits it as linearly polarized light, and emits linearly polarized second display light L2 from the rear surface as approximately circularly polarized light. To achieve this function, the reflective / transmissive member 132 can be configured to include a quarter-lambda plate 132a that converts linearly polarized light into approximately circularly polarized light and a reflective layer 132b. The reflective layer 132b can be a second reflective layer (typically, for example, LCP) that transmits linearly polarized light and reflects approximately circularly polarized light. This LCP reflects specific circularly polarized light with a relatively high reflectance while maintaining the same rotation direction, while transmitting circularly polarized light of a different wavelength from the specific circularly polarized light. In this case, for example, by disposing the reflective layer 132b on the back surface of the ¼λ plate 132a, when a virtual image VI is displayed, approximately half of the second display light from the second display device passes through the LCP, is converted from linearly polarized light to circularly polarized light by the ¼λ plate 132a, and is emitted to the concave mirror 14, and the second display light L2 is emitted from the reflective-transmissive member 132 at, for example, about 50% of the brightness. On the other hand, when a real image RI is displayed, the first display light L1 from the first display device 12a is converted from linearly polarized light to circularly polarized light by the ¼λ plate 132a, is reflected by the LCP as circularly polarized light, is converted again by the ¼λ plate 132a from circularly polarized light to linearly polarized light, and is emitted to the concave mirror 14, and the first display light L1 can be emitted from the reflective-transmissive member 132 while maintaining a high brightness of, for example, 80% or more. In this way, particularly for real image RI, brightness higher than that achieved when a conventional half mirror is used can be achieved.

[0046] Furthermore, when the reflective layer 132b is made of LCP, the second display light L2 is visible to the driver DR in a circularly polarized state. Therefore, even if the driver uses polarized sunglasses (for example, sunglasses that absorb either P-polarized or S-polarized light and transmit the other polarized light), the driver DR can see the image through the other polarized light that is transmitted. [Explanation of symbols]

[0047] C vehicle DR Driver F1,F2 optical focus L1 1st display light L2 2nd display light RI real image VI Virtual Image WS Window Shield 1 HUD device 10a 1st PGU 10b 2nd PGU 11a 1st light source 11b Second light source 12a 1st display 12b 2nd display 14 concave mirror 15 Control Unit 16 Case 17 Opening 18 Coverslips 131 First correcting mirror 132 Reflective and transparent materials 132a 1 / 4λ plate 132b Reflective layer

Claims

1. A head-up display device having an emission port, and emitting display light from the emission port toward a light-transmitting member to allow a virtual image and a real image of a display image represented by the display light to be visually recognized, a first display that emits first display light as linearly polarized light; a second display that emits second display light as linearly polarized light; a reflective / transmissive member that reflects the first display light emitted from the first display device and incident on the front surface thereof to emit the first display light as linearly polarized light, and transmits the second display light emitted from the second display device and incident on the back surface thereof to emit the second display light as approximately circularly polarized light; a concave mirror that reflects the first display light or the second display light emitted from the reflective / transmissive member toward the translucent member; A head-up display device comprising:

2. The reflective / transmissive member is a ¼λ plate that converts linearly polarized light into approximately circularly polarized light; a reflective layer that reflects the first display light or the second display light; 2. The head-up display device according to claim 1, further comprising:

3. The reflective layer is a first reflective layer that reflects linearly polarized light and transmits approximately circularly polarized light, or a second reflective layer that transmits linearly polarized light and reflects approximately circularly polarized light.

3. The head-up display device according to claim 2.

4. When the reflective layer is the first reflective layer, it is disposed in front of the ¼ λ plate, and when the reflective layer is the second reflective layer, it is disposed on the back of the ¼ λ plate.

4. The head-up display device according to claim 3.

5. When the reflective layer is the first reflective layer, it reflects more than half of the linearly polarized light and transmits approximately half of the approximately circularly polarized light, and when the reflective layer is the second reflective layer, it transmits approximately half of the linearly polarized light and reflects more than half of the approximately circularly polarized light.

5. The head-up display device according to claim 4.

6. The first reflective layer is 6. The head-up display device according to claim 3, wherein the head-up display device is a cold mirror film.

7. The second reflective layer is 6. The head-up display device according to claim 3, wherein the display is made of a liquid crystal polymer.

8. A correction mirror for correcting distortion of the first display light is provided between the first display and the reflective / transmissive member along the optical path.

2. The head-up display device according to claim 1.

9. when the first display device emits the first display light, an optical focus of an imaging optical system including the correction mirror, the reflective / transmissive member, the concave mirror, and the light-transmitting member is located closer to the exit port than the first display device along the optical path; When the second display device emits the second display light, an optical focal point of a combined optical system including the reflective / transmissive member, the concave mirror, and the light-transmitting member is located on the opposite side of the second display device from the light outlet along the optical path.

9. The head-up display device according to claim 8.

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