Head-up display device and vehicle

Abstract

Provided is a technique capable of improving utilization efficiency of light. A head-up display device (1) comprises: an image forming unit (10) that emits video light; an imaging optical system that forms a video generated by the image forming unit as a real image on an intermediate screen; and a video projection unit that reflects the video light of the real image formed by the imaging optical system and projects the reflected video light onto a projection member. The image forming unit has a light source (110) that emits light, a display panel (130) that generates a video, and an optical element (100) that splits the light emitted from the light source into a plurality of optical paths and guides the light to the display panel.

Description

Head-up display device and vehicle

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

[0002] For example, vehicles such as automobiles may be equipped with a head-up display (hereinafter, sometimes referred to as "HUD"). HUDs project and display various information, such as driving information such as vehicle speed and engine RPM, and navigation information, onto a windshield (windshield), a combiner, or the like. Using an HUD allows the driver to obtain information necessary for driving without shifting their gaze to an instrument panel, or the like, built into the dashboard. This contributes to safer driving.

[0003] Patent Document 1 describes a HUD technology that directs light emitted from an LED element to a liquid crystal display (LCOS) panel via a polarizing beam splitter (PBS). The LCOS can change the polarization direction of the light, and the PBS transmits or reflects the light depending on the polarization direction, so an image is generated by turning the pixels on the LCOS on and off.

[0004] JP 2012-163613 A

[0005] In the above Patent Document 1, the PBS transmits or reflects light depending on the polarization direction, but the light that passes through the PBS is not used; only the light reflected by the PBS is irradiated onto the LCOS and used to display an image, resulting in low utilization efficiency of the light emitted from the LED element.

[0006] Furthermore, the PBS must have a square surface with a side length equal to the length of the effective area for displaying an image on the LCOS, which results in an increase in size.

[0007] An object of the present invention is to provide a technique capable of improving the light utilization efficiency.

[0008] To solve the above problems, one representative head-up display device of the present invention includes an image forming unit that emits image light, an imaging optical system that forms the image generated by the image forming unit as a real image on an intermediate screen, and an image projection unit that reflects the image light of the real image formed by the imaging optical system and projects the reflected image light onto a projection member. The image forming unit has a light source that emits light, a display panel that generates an image, and an optical element that separates the light emitted from the light source into multiple optical paths and guides them to the display panel.

[0009] According to the present invention, it is possible to improve the light utilization efficiency.

[0010] 1 is a schematic diagram showing a configuration example of a vehicle equipped with a head-up display device of the present embodiment. FIG. 2 is a schematic diagram showing an installation example of the HUD device of the present embodiment. FIG. 3 is a block diagram showing a configuration example of sensors and the like used by a vehicle information acquisition unit of the HUD device 1 or a vehicle controller to acquire vehicle information. FIG. 4 is a block diagram showing a configuration example of functional blocks of the HUD device 1. FIG. 5 is a block diagram showing a modified configuration of the functional blocks of the HUD device 1. FIG. 6 is a diagram showing an example of the configuration of a PGU 10 of Example 1. FIG. 7 is a plan view of a reflective liquid crystal panel of Example 1. FIG. 8 is a diagram showing an example of the configuration of a PGU 10 of Example 2. FIG. 9 is a plan view of a reflective liquid crystal panel of Example 2. FIG. 10 is a diagram showing an example of the configuration of a PGU 10 of Example 3. FIG. 11 is a diagram showing an example of the configuration of a PGU 10 of Example 4. FIG. 12 is a diagram showing an example of the configuration of a PGU 10 of Example 5. FIG. 13 is a diagram showing an example of the configuration of a PGU 10 of Example 6. FIG. 14 is a diagram showing an example of the configuration of a polarization conversion element 140a of Example 6. FIG. 15 is a diagram showing an example of the configuration of a PGU 10 of Example 7. FIG. 16 is a diagram showing an example of the configuration of a PGU 10 of Example 8.

[0011]

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated explanations thereof will be omitted. [Vehicle] Fig. 1 is a schematic diagram showing an example of the configuration of a vehicle equipped with a head-up display device according to an embodiment.

[0012] A head-up display (HUD) device 1 in Fig. 1 is mounted on a vehicle 2. The vehicle 2 is typically an automobile, but is not necessarily limited to this, and may be a vehicle such as a railway car in some cases. The HUD device 1 acquires vehicle information 4 from various sensors installed in various parts of the vehicle 2, a navigation device, etc. The various sensors, for example, detect various events that occur in the vehicle 2 and periodically detect the values ​​of various parameters related to the driving situation.

[0013] The vehicle 2 includes a controller or control unit 8 of the vehicle 2, which is called, for example, an ECU (Electronic Control Unit). The controller 8 controls the driving and other operations of the vehicle 2. The HUD device 1 communicates with the controller 8 via CAN (Controller Area Network) or LIN (Local Interconnect Network) communication, for example. The controller 8 and the HUD device 1 constitute an in-vehicle system of the vehicle 2. The HUD device 1 projects video light onto a display area such as a windshield 3 or a combiner based on vehicle information 4, and displays a virtual image. As a result, the HUD device 1 allows a user, such as a driver, to visually recognize the video light projected onto the display area 5 of the windshield 3 as a virtual image superimposed on the scenery ahead of the vehicle 2.

[0014] The controller 8 controls the HUD device 1 via a CAN signal or the like to display video information as a virtual image in the display area 5. The controller 8 acquires the vehicle information 4 using various sensors, measurement devices, communication devices, and the like as shown in FIG.

[0015] The HUD device 1 receives and acquires vehicle information 4 and the like from the controller 8 via a CAN signal or the like. The HUD device 1 emits image light onto the display area 5 based on the vehicle information 4 and the like, and the image light projected onto the display area 5 can be viewed as a virtual image.

[0016] In Figure 1 and other figures, (X, Y, Z) are used as coordinate systems and directions for explanation. Figure 1 and other figures show a spatial coordinate system relative to the vehicle 2. With respect to the vehicle 2 and the driver, the Z axis and Z direction are the vertical direction, in other words, the up-down direction or longitudinal direction of the vehicle. The X axis and X direction are the first horizontal direction, in other words, the left-right direction, the width direction or lateral direction of the vehicle. The Y axis and Y direction are the second horizontal direction perpendicular to the X axis, in other words, the traveling direction of the vehicle or the front-rear direction of the vehicle.

[0017] 1, the projection image is projected onto the display area 5 of the windshield 3, but the present invention is not limited to this, and the projection image may be projected onto the display area of ​​a projection unit such as a combiner disposed on the vehicle 2. [HUD Device] Fig. 2 is a schematic diagram showing an example of installation of the HUD device 1 of this embodiment.

[0018] FIG. 2 shows a schematic diagram of the vehicle 2 of FIG. 1 as viewed from the X-axis direction on the Y-Z plane. In FIG. 2, the HUD device 1 is mounted in a dashboard 70 of the vehicle 2. The HUD device 1 includes an image forming unit or PGU 10, an imaging optical system 11, a diffuser or intermediate screen 12, and mirrors M2 and M1 within a housing. The optical element or mirror M2 included in the HUD device 1 may be multiple, may not be present, or may be a corrective lens. The optical systems, including the PGU 10, mirror M2, and mirror M1, are disposed and fixed in a predetermined positional relationship within the housing. Furthermore, part or all of the PGU 10 may be disposed and fixed outside the housing.

[0019] An opening 7 through which the image light of the HUD device 1 is emitted is provided in a part of the housing of the HUD device 1 and in a part of the dashboard 70. The opening 7 may be provided with a dustproof cover made of a transparent member or the like.

[0020] The PGU 10 emits linearly or circularly polarized light to form an image. The image created by the PGU 10 is then projected as a real image onto a diffuser or intermediate screen 12 by an imaging optical system 11. The imaging optical system 11 may be a lens or a mirror. The intermediate screen 12 is, for example, a transmissive screen with a Fresnel lens shape on one side and a lenticular lens or diffusing surface on the other side. The diffuser or intermediate screen 12 diffuses the projected light. Disturbances in polarization due to the diffuser or intermediate screen 12 can result in differences in brightness depending on the location of the projected image, so it is desirable to use a diffuser 12 with low retardation. On the other hand, a diffuser with high retardation is installed so that its slow axis is perpendicular or parallel to the polarization axis of the image.

[0021] The mirror M2 may be, for example, a flat mirror or a folding mirror. In this embodiment, the mirror M2 is a folding mirror that reflects the image light diffused by the diffuser 12 toward the mirror M1. The mirror M1 functions as an image projection unit that magnifies and reflects the image light from the folding mirror M2 in a direction at a set angle or in a predetermined direction. The mirror M1 is, for example, a free-form mirror or a mirror having an asymmetric shape about its optical axis. In this embodiment, the mirror M1 is a mirror having a concave reflective surface.

[0022] The angle or orientation of the mirror M1 can be adjusted by the mirror driver 1020. This allows the display area 5 and virtual image display position of the windshield 3 to be adjusted to match the driver's eye height. The mirror driver 1020 is a mechanism including a stepping motor or the like, and adjusts the installation angle of the mirror M1. Alternatively, the installation angle of the mirror M1 may be adjustable based on manual operation by the user. Furthermore, by changing the area of ​​the mirror M1, the area of ​​the display area 5 can be adjusted, making it possible to project an appropriate amount of information onto the display area 5.

[0023] 2 only shows the rotation mechanism of the mirror M1, i.e., the mechanism for adjusting the display area 5 in the vertical direction. The mirror M1 may also have a mechanism for adjusting the display area 5 in the horizontal direction. Also, one rotation mechanism may be capable of adjusting the display area 5 in both the vertical and horizontal directions.

[0024] As shown in the figure, the image light from the PGU 10 is reflected by the folding mirror M2 and the mirror M1, and then emitted from the opening 7, projected onto the display area 5 of the windshield 3, reflected by the windshield 3, and directed toward the driver's viewpoint 6. In the present invention, the windshield 3 is used for description, but the image light may also be projected onto the projection area of ​​a projection member other than the windshield 3, such as a combiner. As a result, when the driver looks forward (forward along the Y axis) from the driver's viewpoint 6, the image light projected onto the display area 5 of the windshield 3 can be viewed as a virtual image 9. In the display area 5, a virtual image formed by the image light is displayed superimposed on the actual forward view. In the case of non-Augmented Reality (AR), the virtual image 9 is image information displayed independently at a predetermined position. In the case of AR, the virtual image 9 is image information superimposed according to the position of an object. Examples of image information that becomes the virtual image 9 include information such as vehicle speed, navigation information, and alert information. 3 is a block diagram showing an example of the configuration of sensors and the like used by the control unit 1001 ( FIG. 4A ) of the HUD device 1 or the controller 8 of the vehicle 2 to acquire the vehicle information 4. As shown in FIG. 4B , the HUD device 1 does not necessarily have to include the control unit 1001. In this case, the controller 8 of the vehicle 2 may function as the control unit 1001 of the HUD device 1.

[0025] 3 shows examples of various sensors, in other words, information acquisition devices, measurement devices, communication devices, etc., connected to the control unit 1001 or the controller 8. For example, the control unit 1001 acquires vehicle information 4 from sensors or cameras of the vehicle 2. Alternatively, the controller 8 acquires vehicle information 4 from sensors installed in various parts of the vehicle 2 and transmits the vehicle information 4 to the HUD device 1. The various sensors periodically detect parameter values ​​related to conditions such as driving conditions inside and outside the vehicle 2. Furthermore, the controller 8 determines and detects various events related to the vehicle 2 based on the information detected by the sensors.

[0026] Vehicle information 4 is a general term for information related to the driving status of the vehicle 2. The vehicle information 4 includes ADAS information and the like. The vehicle information 4 includes, for example, the speed information and gear information of the vehicle 2, steering angle information, lamp illumination information, external light information, distance information, infrared information, engine ON / OFF information, camera image information, acceleration gyro information, GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and road-to-vehicle communication information. The camera image information includes in-vehicle camera image information and outside-vehicle camera image information. The GPS information includes current time information, latitude and longitude information.

[0027] 3 , the various sensors include a vehicle speed sensor 901, a shift position sensor 902, a steering wheel steering angle sensor 903, a headlight sensor 904, an illuminance sensor 905, a chromaticity sensor 906, a distance measurement sensor 907, an infrared sensor 908, an engine start sensor 909, an acceleration sensor 910, a gyro sensor 911, a temperature sensor 912, a wireless transceiver for road-to-vehicle communication 913, a wireless transceiver for vehicle-to-vehicle communication 914, an in-vehicle camera 915, an outside-vehicle camera 916, a GPS receiver 917, and a VICS (Vehicle Information and Communication System, registered trademark) receiver 918. The various sensors are not limited to these, and addition, deletion, replacement, etc. are possible.

[0028] The vehicle speed sensor 901 detects the speed of the vehicle 2 (also referred to as vehicle speed) and generates speed information representing the detection result. The shift position sensor 902 detects the current gear and generates gear information representing the detection result. The steering wheel steering angle sensor 903 detects the current steering wheel steering angle and generates steering wheel steering angle information representing the detection result. The headlight sensor 904 detects whether the headlights are on or off and generates lamp illumination information representing the detection result. The illuminance sensor 905 and chromaticity sensor 906 detect external light and generate external light information representing the detection result.

[0029] The distance sensor 907 detects the distance between the vehicle 2 and an external object and generates distance information as the detection result. The infrared sensor 908 detects the presence or absence of an object in the vicinity of the vehicle 2 and the distance, and generates infrared information as the detection result. The engine start sensor 909 detects whether the engine is on or off and generates on or off information as the detection result. The acceleration sensor 910 and gyro sensor 911 detect the acceleration and angular velocity of the vehicle 2 and generate acceleration gyro information representing the attitude and behavior of the vehicle 2 as the detection result. The temperature sensor 912 detects the temperature inside and outside the vehicle 2 and generates temperature information as the detection result.

[0030] The in-vehicle camera 915 captures images of the interior of the vehicle 2 to generate in-vehicle camera video information. The exterior camera 916 captures images of the exterior of the vehicle 2 to generate exterior camera video information. In a specific example, the camera 90 in FIG. 2 corresponds to the in-vehicle camera 915 and the exterior camera 916. The in-vehicle camera 915 captures, for example, the driver's posture, eye position, and movement, constituting a driver monitoring system (DMS). By analyzing the in-vehicle camera video information, it is possible to grasp the driver's fatigue level and line of sight. The exterior camera 916 also captures images of the surrounding environment, such as the area ahead of the vehicle 2. By analyzing the exterior camera video information, it is possible to grasp the presence or absence of other vehicles and people around the vehicle 2, buildings and terrain, road conditions such as rain, snow, ice, and unevenness, and road signs. The exterior camera 916 also includes a drive recorder that records video of the driving situation.

[0031] The road-to-vehicle communication wireless transceiver 913 generates road-to-vehicle communication information through road-to-vehicle communication between the vehicle 2 and roads, signs, traffic lights, etc. The vehicle-to-vehicle communication wireless transceiver 914 generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between the vehicle 2 and other vehicles in the vicinity. The GPS receiver 917 generates GPS information by receiving GPS signals from GPS satellites. For example, the current time, latitude, and longitude can be acquired as GPS information. The VICS receiver 918 generates VICS information by receiving VICS signals. The GPS receiver 917 and the VICS receiver 918 may be provided as part of a navigation system.

[0032] Fig. 4A is a block diagram showing an example of the configuration of functional blocks of the HUD device 1. In Fig. 4A, the HUD device 1 includes a control unit 1001, a video display unit 200, a mirror driving unit 1020, a display driver 1021, a light source driving unit 1022, an audio driver 1025, an audio output device 1041, an audio input device 1042, etc. The control unit 1001 includes an MCU (microcontrol unit) 1010, a non-volatile memory 1011, a volatile memory 1012, a video processing unit 1013, an audio processing unit 1014, a vehicle information acquisition unit 1015, a communication unit 1016, an operation input unit 1017, etc. These units are connected to each other via a bus or the like, and are capable of inputting, outputting, and communicating with each other.

[0033] In other words, the control unit 1001 is a control device. The control unit 1001 realizes control functions and the like based on processing by the processor. The control functions are functions for controlling the entire HUD device 1 and each component, and include a function for displaying a virtual image 9 in the display area 5. The control unit 1001 realizes its functions by software program processing or a dedicated circuit.

[0034] The storage unit of the HUD device 1 is configured to include a nonvolatile memory 1011 and a volatile memory 1012. In this embodiment, the storage unit is configured to include both the nonvolatile memory 1011 and the volatile memory 1012, but the above configuration may function as a single memory. The storage unit stores various data and information handled by the control unit 1001, etc., including computer programs.

[0035] The communication unit 1016 is a device equipped with a communication interface. The communication unit 1016 is connected to and capable of communicating with the controller 8 (e.g., an electronic control unit (ECU)) via an interface such as a controller area network (CAN) or a local interconnect network (LIN) of the vehicle 2.

[0036] The mirror driving unit 1020 is a device that drives the mirror M1 based on the control from the control unit 1001.

[0037] The display driver 1021 is a device including a drive circuit and the like that drives the display panel 130 of the PGU 10 based on control from the control unit 1001. The display panel in the following embodiments will be described using a reflective liquid crystal panel (LCOS).

[0038] The light source driving unit 1022 is a device including a driving circuit and the like that drives the light source device 110 of the PGU 10 based on control from the control unit 1001. The light source driving unit 1022 has a driving circuit and the like that can change the on / off and light intensity of the light emission of each light source element of the light source device 110.

[0039] The audio input device 1042 is configured with a microphone, a circuit, etc. The audio output device 1041 is configured with a speaker, a circuit, etc. Note that, although the case where the HUD device 1 is provided with the audio input device 1042 and the audio output device 1041 is illustrated, this is not limiting, and the HUD device 1 may use the audio input device 1042 and the audio output device 1041 that are externally connected to the vehicle 2, for example, the controller 8.

[0040] 4A acquires input information such as vehicle information 4 ( FIG. 1 ), ADAS information, and event information through a vehicle information acquisition unit 1015. Alternatively, the control unit 1001 acquires input information such as vehicle information 4 ( FIG. 1 ), ADAS information, and event information as a CAN signal from the controller 8 through a communication unit 1016. The vehicle information acquisition unit 1015 may be implemented integrally with the communication unit 1016.

[0041] The input information includes detection signals from various sensors as shown in FIG. 3 or information resulting from processing the same by the controller 8. The input information also includes, for example, information on objects in the real scene detected based on images from the cameras 915 and 916, as well as alert information and navigation information to be superimposed on the objects. The control unit 1001 uses its control function to generate video data and video information to be displayed as a virtual image 9 in the display area 5 as necessary based on such input information. The control unit 1001 generates video signals and the like for controlling the display driver 1021 and the like based on the video data and video information.

[0042] The control unit 1001 may also acquire operation input information from a user through the operation input unit 1017. Examples of the operation input unit 1017 include a remote control. When audio is output from the HUD device 1, the control unit 1001 generates audio output information and controls the audio driver 1025. When inputting the voice of a user such as a driver, the control unit 1001 performs voice recognition based on the input voice of the audio input device 1042 and accepts predetermined instructions, etc.

[0043] 4A , the HUD device 1 may include, for example, various sensors. The control unit 1001 may use the detection information of the sensors to determine and detect the state of the HUD device 1 and the state near the HUD device 1, and perform predetermined control.

[0044] FIG. 4B is a block diagram showing a modified example of the functional blocks of the HUD device 1. In FIG. 4B, the controller 8 of the vehicle 2 functions as the control unit 1001 of FIG. 4A. The basic control of FIG. 4B is the same as that of FIG. 4A, and only the differences will be described here. As shown in FIG. 4B, the HUD device 1 does not have the control unit 1001. All information is received by the vehicle information acquisition unit 1015 and the transmission unit 1016, and a projected image (virtual image) is displayed based on the received signal, and audio output is performed. Furthermore, unlike the function of the image processing unit 1013 of FIG. 4A, the image processing unit 1013 of FIG. 4B does not create an image, but instead processes (e.g., decodes) and displays the image received from the vehicle 2. On the other hand, if the image processing unit 1013 of FIG. 4B is not included, processing may be performed within the MCU. The vehicle information acquisition unit 1015 and the transmission unit 1016 may be integrated into one unit.

[0045] 4A and 4B may be mounted inside the housing of the HUD device 1 in FIG. 3 or the like, or may be connected outside the housing. [First Embodiment] Fig. 5A is a diagram showing an example of the configuration of the PGU 10 of the first embodiment. Fig. 5B is a plan view of the reflective liquid crystal panel of the first embodiment.

[0046] 5A , the PGU 10 includes a light source device 110, an illumination optical system 120, a PBS or polarization separation element 100, and a reflective liquid crystal panel or LCOS 130. The PBS 100 includes glass plates 101 a, 101 b, and 101 c, polarization separation films 102 a and 102 b, a retardation film (¼λ) 103, and a mirror 104.

[0047] The light source device 110 uses, for example, a relatively inexpensive and highly reliable LED (Light Emitting Diode) as a solid-state light source. A single light source may be used, or multiple light sources may be arranged in an array. In FIGS. 5 to 12, a coordinate system and directions (x', y', z') are used for illustrative purposes. The x', y', and z' axes are perpendicular to one another, and the z' axis is parallel to the optical axis of the image light emitted by the LCOS 130. The x' axis is parallel to the short side of the LCOS 130. The y' axis is parallel to the long side of the LCOS 130.

[0048] The illumination optical system 120 in this embodiment is composed of a collimating lens or the like, and takes in light emitted from the light source device 110 and converts it into parallel or nearly parallel light. The optical element splits the light emitted from the light source device 110 into multiple optical paths and guides the light to the display panel 130 or the reflective liquid crystal panel 130. The optical element in this embodiment includes a polarizing element 100 or a PBS 100 (Polarizing Beam Splitter: PBS) that transmits one of mutually orthogonal linearly polarized light (or a portion of the linearly polarized light) and reflects the other (or a portion of the linearly polarized light other than the transmitted linearly polarized light, or a portion of the linearly polarized light other than the transmitted linearly polarized light), and a retardation film 103 that rotates the polarization axis of the linearly polarized light transmitted through or reflected by the polarizing element 100 or the PBS 100 by 90°. Randomly polarized light emitted from the light source of the light source device 110 is converted into linearly polarized light by the polarizing element 100 or the PBS 100 and the retardation film 103. The polarizing element 100 or PBS 100 may be a plate type made of flat glass or a cube type combining a rectangular prism. The polarizing element 100 or PBS 100 converts the polarization of light transmitted through the illumination optical system 120 to a desired polarization direction in order to improve the utilization efficiency of light from the light source of the light source device 110. This improves the efficiency of light incident on the reflective liquid crystal panel 130. The polarizing element 100 or PBS 100 has a transparent member 101 and a polarization separation film 102. The transparent member 101 may be a parallelogram-shaped or triangular-shaped translucent member, and the polarization separation film 102 may be a reflective polarizing film or a dielectric multilayer film. The polarizing element 100 or PBS 100 further includes a plurality of transparent members 101 joined together, with the polarization separation film 102 disposed on the joining surfaces of the transparent members 101. In this embodiment, the transparent member 101 is made of a plurality of glass plates or glass plates and has a triangular shape in the y'z' cross section. In this embodiment, the glasses 101a, 101b, and 101c are prisms and have a shape such that the PBS 100 is a rectangular parallelepiped.

[0049] The polarization separation films 102a and 102b are, for example, dielectric multilayer films that separate incident light into P-polarized and S-polarized light, transmitting P-polarized light vibrating in the y'z'-plane direction (incident plane direction) and reflecting S-polarized light vibrating in the direction perpendicular to the incident plane (x'-axis direction). The polarization separation film 102a is provided on one of the surfaces of the glass 101a and glass 101b, and the polarization separation film 102b is provided on one of the surfaces of the glass 101b and glass 101c. Alternatively, the polarization separation films are disposed / attached to the bonding surface between the glass plates.

[0050] The retardation film (1 / 4λ) 103 gives a phase difference of 1 / 4λ to the incident linearly polarized light and outputs it. When the polarization axis of the incident linearly polarized light intersects with the slow axis of the retardation film at 45°, the light that passes through the retardation film (1 / 4λ) 103 is converted into circularly polarized light. The mirror 104 reflects the light.

[0051] The LCOS 130 generates video light by modulating incident light based on a video signal from the display driver 1021. As shown in Figures 5A and 5B, the LCOS 130 of this embodiment is divided into area A and area B, or is divided into left and right halves along the long side (y' axis) of the LCOS 130. This results in different light paths entering / exiting area A and area B of the LCOS 130, and therefore different illumination ranges, brightness, colors, etc. In order to make the brightness and color of light entering / exiting area A and area B of the LCOS 130 the same, the LCOS gradation is adjusted separately for area A and area B.

[0052] Light emitted from light source device 110 is incident on polarization splitting film 102a via illumination optical system 120 and glass 101a. Of the light incident on polarization splitting film 102a, linearly polarized light (S-polarized light) vibrating in the x'-axis direction is reflected by polarization splitting film 102a and enters area A of reflective liquid crystal panel 130. On the other hand, of the light incident on polarization splitting film 102a, linearly polarized light (P-polarized light) vibrating in the y'z'-plane direction is transmitted through polarization splitting film 102a. The y'z'-plane direction is the direction parallel to the y'z' plane.

[0053] The light transmitted through the polarization separation film 102a passes through the glass 101b and then through the polarization separation film 102b. The light transmitted through the polarization separation film 102b passes through the glass 101c and the phase difference film (¼λ) 103, and is reflected by the mirror 104.

[0054] The light reflected by the mirror 104 passes through the retardation film (¼λ) 103 , passes through the glass 101 c , is reflected by the polarization separation film 102 b , and the reflected light enters the region B of the reflective liquid crystal panel 130 .

[0055] Light emitted from the light source device 110 passes through the glass 101c and enters the retardation film 103. By passing through the retardation film (1 / 4λ) 103 twice, the polarization direction of the light rotates by 90 degrees, and the light becomes linearly polarized light (S-polarized light) vibrating in the x'-axis direction. In other words, the light that passes through the polarization separation film 102b is converted into circularly polarized light by passing through the retardation film (1 / 4λ) 103, and is further reflected by the mirror 104. By passing through the retardation film (1 / 4λ) 103 again, the light becomes linearly polarized light whose polarization direction has rotated by 90 degrees. As a result, the light reflected by the mirror 104 becomes linearly polarized light (P-polarized light) vibrating perpendicular to the x'-axis direction, and is reflected by the polarization separation film 102b toward the reflective liquid crystal panel 130.

[0056] The light irradiated onto areas A and B of the reflective liquid crystal panel 130 is reflected by the reflective liquid crystal panel 130 and modulated into linearly polarized light (P-polarized light) oscillating in the y'z' plane. The light then passes through the PBS 100 again and is emitted to the diffuser plate 12 via the imaging optical system 11. When the real image formed by the diffuser plate 12 is incident on the windshield 3 as image light, the PGU 10 is preferably positioned so that the image light is incident on the windshield 3 as S-polarized light (approximately in the X-axis direction in FIG. 1 ), so that the image light is reflected with high reflectivity. On the other hand, if the driver wears polarized sunglasses, it is preferable to provide a retardation film on the exit side of the PBS 100 so that the image light is emitted as circularly polarized light or randomly polarized light.

[0057] The light irradiated onto area A and area B of the reflective liquid crystal panel 130 have different optical paths that pass through the PBS 100. Therefore, when the light diverges, the light is irradiated onto a wider area of ​​area B than area A, and when the light is condensed, the light is irradiated onto area B in a narrower area than area A. This problem can be solved by converting the light incident on the PBS 100 into approximately parallel light using the illumination optical system 120. The irradiation range may also be adjusted using the shape of the reflective surface of the mirror 104. Meanwhile, the light irradiated onto area A and area B have different optical paths, resulting in differences in brightness and color. However, by adjusting the grayscale of the LCOS 130, the brightness and color of the image light emitted from area A and area B can be matched.

[0058] According to the first embodiment, the S-polarized light and the P-polarized light separated by the polarization separation film 102a are guided to the LCOS 130 via different optical paths, and the range of incidence of the light entering the LCOS 130 differs depending on the optical path. Furthermore, the P-polarized light transmitted through the polarization separation film 102a is converted to S-polarized light using the retardation film (¼λ) 103 and the mirror 104, and is then used as light for forming an image. In other words, by providing the PGU 10 with an optical path through which both the S-polarized light and the P-polarized light separated by the polarization separation film 102a are used for image generation, the utilization efficiency of the light emitted from the light source device 110 can be improved. The S-polarized light is linearly polarized light that vibrates in the x'-axis direction, and the P-polarized light is linearly polarized light that vibrates in the y'z'-plane direction. Furthermore, the length of the PBS 100 in the z'-axis direction can be set to approximately half the length of the LCOS 130 in the y'-axis direction, thereby enabling the PBS 100 and the illumination optical system 11 to be miniaturized, thereby enabling the entire PGU 10 to be miniaturized. [Embodiment 2] Fig. 6A is a diagram showing an example of the configuration of the PGU 10 of embodiment 2. Fig. 6B is a plan view of a reflective liquid crystal panel of embodiment 2.

[0059] In Example 2, light reflected from an LCOS (reflective liquid crystal display) panel 130 is output from the light output side of the image forming unit 10 via a PBS 100. This example differs from Example 1 in that a retardation film (½λ) 105 is provided on the light output side of the PBS 100 and is arranged so that the direction of light from the light source device 110 to the PBS 100 is in the x'-axis direction. A second retardation film 105 is arranged on the light output side of the image forming unit, separate from a first retardation film 103 arranged in the optical path of linearly polarized light (P-polarized light) oscillating in the z'x'-plane direction among light emitted from the light source. The second retardation film 105 converts the linearly polarized light output from the image forming unit 10 into circularly polarized light or randomly polarized light, which is then incident on the image projection unit. The retardation film (½λ) 105 imparts a phase difference of ½λ to the incident linearly polarized light and outputs it. When the polarization axis of linearly polarized light incident on the retardation film (1 / 2λ) 105 intersects with the slow axis of the retardation film at approximately 45°, the polarization direction of the light transmitted through the retardation film (1 / 2λ) 105 rotates by 90 degrees.

[0060] 6B , in this embodiment, the length of the LCOS 130 in the x′-axis direction is shorter than the length of the LCOS 130 in the y′-axis direction. The retardation film 105 is disposed between the PBS 100 and the imaging optical system 11 in the optical path in the emission direction of the light reflected by the LCOS 130.

[0061] 6A, light from light source device 110 travels on the x' axis, passes through PBS 100, and is irradiated onto LCOS 130. Light incident on regions A and B of LCOS (reflective liquid crystal panel) 130 is reflected by LCOS (reflective liquid crystal panel 130), converted into linearly polarized light (P-polarized light) that vibrates in the z'x' plane, and then passes through PBS 100 again.

[0062] The light that passes through the PBS 100 again passes through a retardation film (½λ) 105, where its polarization direction is rotated by 90 degrees, becoming linearly polarized light (S-polarized light) vibrating in the y′-axis direction, and then entering the diffuser plate 12 via the imaging optical system 11. When the real image formed by the diffuser plate 12 is incident on the windshield 3 as image light, it is desirable to position the PGU 10 so that the image light is incident on the windshield 3 as S-polarized light (approximately in the X-axis direction in FIG. 1 ), so that the image light is reflected with high reflectivity. On the other hand, if the driver wears polarized sunglasses, it is desirable to provide a retardation film 105 on the light exit side of the PBS 100 and output the image light as circularly polarized light or randomly polarized light.

[0063] According to the second embodiment, the S-polarized light and the P-polarized light separated by the polarization separation film 102a are guided to the LCOS 130 via different optical paths, and the range of incidence of the light entering the LCOS 130 differs depending on the optical path. Furthermore, the P-polarized light transmitted through the polarization separation film 102a is converted to S-polarized light using the retardation film (¼λ) 103 and the mirror 104, and is then used as light for forming an image. In other words, by providing the PGU 10 with an optical path through which both the S-polarized light and the P-polarized light separated by the polarization separation film 102a are used for image generation, the utilization efficiency of the light emitted from the light source device 110 can be improved. The S-polarized light is linearly polarized light that vibrates in the y'-axis direction, and the P-polarized light is linearly polarized light that vibrates in the z'x'-plane direction. Furthermore, since the length of the PBS 100 in the z'-axis direction can be approximately half the length of the LCOS 130 in the x'-axis direction, the PBS 100 and the illumination optical system 11 can be further miniaturized, thereby enabling the overall miniaturization of the PGU 10. Here, since the length of the LCOS 130 in the x'-axis direction is shorter than the length in the y'-axis direction, in Example 2, the PBS 100 and the PGU 10 can be further miniaturized. Furthermore, in the configuration of Example 1, the incident range on the LCOS 130 is divided line-symmetrically with respect to a line parallel to the x'-axis, while in the configuration of Example 2, it is divided line-symmetrically with respect to a line parallel to the y'-axis. As described above, the divided incident ranges on the LCOS 130, Regions A and B, are prone to differences in brightness and color. Typically, when a driver views a scene, the further up the viewpoint, the more distant the scene is perceived, and the further down the viewpoint, the closer the scene is perceived. Therefore, when the viewpoint moves up and down, the brightness and color of the background change relatively significantly. In other words, in the HUD, a configuration in which the virtual image 9 is divided in the vertical direction (vertical direction of the vehicle), i.e., the configuration of Example 2, is more suitable for the PGU 10 because the difference in brightness and color between Area A and Area B is less likely to be visible due to changes in brightness and color of the background. [Example 3] Figure 7 is a diagram showing an example of the configuration of the PGU 10 of Example 3.

[0064] 7, the PBS 100 includes glass plates 101a, 101b, 101c, and 101d, and polarization separation films 102a and 102b. The joint surface between the glass plates 101a and 101b is parallel to the joint surface between the glass plates 101c and 101d, and the joint surface between the glass plates 101a and 101b is parallel to the joint surface between the glass plates 101a and 101b, and the polarization separation film 102b is parallel to the joint surface between the glass plates 101c and 101d. A retardation film (½λ) 105 is disposed between the glass plates 101b and 101c.

[0065] The polarization separation film 102a may be provided on either the surface of the glass 101a or the glass 101b. The polarization separation film 102b may be provided on either the surface of the glass 101c or the glass 101d. The retardation film (½λ) 105 is provided between the glass 101b and the glass 101c. That is, the retardation film (½λ) 105 is provided in the optical path of linearly polarized light (P-polarized light) that oscillates in the y'z' plane, out of the light emitted from the light source of the light source device 110. Specifically, the retardation film (½λ) 105 is provided between the optical path entering / exiting region A of the LCOS 130 and the optical path entering / exiting region B.

[0066] Of the light incident on the polarization separation film 102a, linearly polarized light (S-polarized light) vibrating in the x'-axis direction in Fig. 7 is reflected by the polarization separation film 102a and is irradiated onto area A of the reflective liquid crystal panel 130. On the other hand, of the light incident on the polarization separation film 102a, linearly polarized light (P-polarized light) vibrating in the y'z'-plane direction in Fig. 7 is transmitted through the polarization separation film 102a.

[0067] The light that has passed through the polarization separation film 102a passes through the glass 101b and then through the retardation film (½λ) 105, where its polarization direction is rotated by 90 degrees, becoming linearly polarized light (S-polarized light) that vibrates in the x'-axis direction. The light that has passed through the retardation film (½λ) 105 passes through the glass 101c, is reflected by the polarization separation film 102b, and enters region B of the LCOS (reflective liquid crystal panel) 130.

[0068] The light irradiated onto areas A and B of the LCOS (reflective liquid crystal panel) 130 is reflected by the LCOS (reflective liquid crystal panel) 130 and converted into linearly polarized light (P-polarized light) oscillating in the y'z' plane. The light then passes through the PBS 100 again and enters the diffuser plate 12 via the imaging optical system 11. When the real image formed by the diffuser plate 12 is incident on the windshield 3 as image light, the PGU 10 is preferably positioned so that the image light is incident on the windshield 3 as S-polarized light (approximately in the X-axis direction in FIG. 1 ), so that the image light is reflected with high reflectivity. On the other hand, if the driver wears polarized sunglasses, it is preferable to provide a retardation film on the light exit side of the PBS 100 so that the image light is emitted as circularly polarized light or randomly polarized light.

[0069] According to the third embodiment, the S-polarized light and the P-polarized light separated by the polarization separation film 102a are guided to the LCOS 130 via different optical paths, and the range of incidence of light entering the LCOS 130 differs depending on the optical path. Furthermore, the P-polarized light transmitted through the polarization separation film 102a is converted to S-polarized light by the retardation film (½λ) 105 and used as light for forming an image. That is, by providing the PGU 10 with an optical path in which both the S-polarized light and the P-polarized light separated by the polarization separation film 102a are used for image generation, the utilization efficiency of light emitted from the light source device 110 can be improved. Furthermore, the length of the PBS 100 in the z′-axis direction can be approximately half the length of the LCOS 130 in the y′-axis direction, thereby enabling the miniaturization of the PBS 100 and the illumination optical system 11, and thus the overall PGU 10. Although not shown, similar to the relationship between the first and second embodiments, the configuration of the third embodiment also allows the light source 110 to be arranged so that its optical axis is parallel to the x′-axis. In this case, the length of the PBS 100 in the z'-axis direction is half the length of the LCOS 130 in the x'-axis direction, and the areas A and B, which are the incident ranges on the LCOS 130, are in a line-symmetric relationship with respect to a line parallel to the y'-axis.

[0070] Furthermore, since the difference in the optical paths between area A and area B is smaller than in Example 1, the difference in the illumination range is smaller, and it is possible to reduce the difference in brightness and color between area A and area B. Example 4 Fig. 8 is a diagram showing an example of the configuration of a PGU 10 according to Example 4.

[0071] 8 , PBS 100 includes glass plate 101a having a triangular shape in the y'z' cross section, glass plate 101b having a parallelogram shape in the y'z' cross section, glass plate 101c having a triangular shape in the y'z' cross section, and reflective polarizing films 106a and 106b. Glass plate 101b having a parallelogram shape in the cross section is disposed between glass plate 101a having a triangular cross section and glass plate 101c having a triangular cross section. Retardation film (½λ) 105 is disposed in the direction in which light reflected by region B of reflective liquid crystal panel 130 passes through glass plate 101c and exits, or is disposed in the optical path between the light exit side of PBS 100 and diffuser plate 12 in the exit direction of light reflected by region B of reflective liquid crystal panel 130. The size of retardation film (½λ) 105 is approximately the same as that of region B.

[0072] The reflective polarizing films 106a and 106b have a transmission axis that transmits linearly polarized light and a reflection axis that reflects linearly polarized light, and the transmission axis and reflection axis are orthogonal to each other. Therefore, the reflective polarizing films 106a and 106b provided on the glasses 101a, 101b, and 101c can transmit / reflect any linearly polarized light by adjusting the angle of the transmission axis (or reflection axis). Examples of reflective polarizing films that can be used include wire grid films with nanostructures and multilayer films in which optically isotropic films and optically anisotropic films are alternately laminated.

[0073] The reflective polarizing film 106a is provided on one of the surfaces between the glass plates 101a and 101b so as to transmit linearly polarized light oscillating in the y'z'-plane direction and reflect linearly polarized light oscillating in the x'-axis direction. The reflective polarizing film 106b is provided on one of the surfaces between the glass plates 101b and 101c so as to reflect linearly polarized light oscillating in the y'z'-plane direction and transmit linearly polarized light oscillating in the x'-axis direction. The transmission axis angles (or reflection axis angles) of the reflective polarizing films 106a and 106b may be reversed. That is, the reflective polarizing film 106a reflects linearly polarized light oscillating in the y'z'-plane direction and transmits linearly polarized light oscillating in the x'-axis direction, while the reflective polarizing film 106b reflects linearly polarized light oscillating in the y'z'-plane direction and transmits linearly polarized light oscillating in the x'-axis direction.

[0074] Of the light incident on the reflective polarizing film 106a, linearly polarized light oscillating in the x'-axis direction in Fig. 8 is reflected by the reflective polarizing film 106a and is irradiated onto area A of the LCOS (reflective liquid crystal panel) 130. On the other hand, of the light incident on the reflective polarizing film 106a, linearly polarized light oscillating in the y'z'-plane direction in Fig. 8 is transmitted through the reflective polarizing film 106a.

[0075] The light transmitted through the reflective polarizing film 106 a passes through the glass 101 b , is reflected by the reflective polarizing film 106 b , and is incident on the region B of the LCOS (reflective liquid crystal panel) 130 .

[0076] The light incident on area A of the LCOS (reflective liquid crystal panel) 130 is reflected by the reflective liquid crystal panel 130 and modulated into linearly polarized light vibrating in the y'z' plane, then passes through the PBS 100 again and enters the diffuser 12 via the imaging optical system 11.

[0077] The light incident on region B of the reflective liquid crystal panel 130 is reflected by the reflective liquid crystal panel 130 and modulated into linearly polarized light oscillating in the x'-axis direction, and then passes through the PBS 100 again. The light then passes through the retardation film (½λ) 105, where it is converted into linearly polarized light oscillating in the y'z'-plane direction, and then passes through the imaging optical system 11 and enters the diffuser 12. The retardation film (½λ) 105 may be provided on the glass 101b that forms the exit surface of the PBS 100. In this case, the image light emitted from region A of the LCOS 130 passes through the retardation film (½λ) 105, whereby it is converted from linearly polarized light oscillating in the y'z'-plane direction to linearly polarized light oscillating in the x'-axis direction. The image light emitted from region B of the LCOS 130 exits the PBS 100 as linearly polarized light oscillating in the x'-axis direction. That is, the image light emitted from the PGU 10 is aligned into linearly polarized light vibrating in the x'-axis direction and then emitted.

[0078] According to the fourth embodiment, the orthogonal linearly polarized light beams separated by the reflective polarizing film 106a are guided to the LCOS 130 via different optical paths, and the range of incidence of the light entering the LCOS 130 varies depending on the optical path. Furthermore, the linearly polarized light beams oscillating in the y'z' plane that have passed through the reflective polarizing film 106a are converted by the retardation film (½λ) 105 into linearly polarized light beams oscillating in the x'-axis direction, and are then used as light for forming an image. In other words, by providing the PGU 10 with an optical path in which both of the orthogonal linearly polarized light beams separated by the reflective polarizing film 106a are used for image generation, the utilization efficiency of the light emitted from the light source device 110 can be improved. Furthermore, the length of the PBS 100 in the z'-axis direction can be approximately half the length of the LCOS 130 in the y'-axis direction, thereby enabling the PBS 100 and the illumination optical system 11 to be miniaturized, and the entire PGU 10 to be miniaturized. Although not shown, the configuration of Example 4 can also be configured so that the optical axis of light source 110 is parallel to the x'-axis, similar to the relationship between Examples 1 and 2. In this case, the length of PBS 100 in the z'-axis direction is half the length of LCOS 130 in the x'-axis direction, and areas A and B, which are the incidence ranges on LCOS 130, are in a line-symmetric relationship with respect to a line parallel to the y'-axis.

[0079] Furthermore, compared to Example 1, the difference in the optical paths between area A and area B is small, so the difference in the illumination range is small, and it is possible to reduce the difference in brightness and color between area A and area B. Example 5 Fig. 9 is a diagram showing an example of the configuration of a PGU 10 according to Example 5.

[0080] 9, the PBS 100 includes glass plates 107a and 107b and reflective polarizing films 106a and 106b. A retardation film (½λ) 105 is provided between the reflective polarizing film 106b and the glass plate 107b.

[0081] The reflective polarizing film 106a is provided on one surface of the glass plate 107a so as to transmit linearly polarized light vibrating in the y'z'-plane direction and reflect linearly polarized light vibrating in the x'-axis direction. The reflective polarizing film 106b is provided on one surface of the glass plate 107b so as to reflect linearly polarized light vibrating in the y'z'-plane direction and transmit linearly polarized light vibrating in the x'-axis direction. The retardation film (½λ) 105 is provided between the reflective polarizing film 106b and the glass plate 107b or on the exit side of the glass plate 107b. The transmission axis angle (or reflection axis angle) of the reflective polarizing films 106a and 106b may be reversed. That is, reflective polarizing film 106a reflects linearly polarized light vibrating in the y'z' plane direction and transmits linearly polarized light vibrating in the x' axis direction, while reflective polarizing film 106b reflects linearly polarized light vibrating in the y'z' plane direction and transmits linearly polarized light vibrating in the x' axis direction.

[0082] Of the light incident on the reflective polarizing film 106a, linearly polarized light oscillating in the x'-axis direction in Fig. 9 is reflected by the reflective polarizing film 106a and is irradiated onto area A of the reflective liquid crystal panel 130. On the other hand, of the light incident on the reflective polarizing film 106a, linearly polarized light oscillating in the y'z'-plane direction in Fig. 9 is transmitted through the reflective polarizing film 106a.

[0083] The light transmitted through the reflective polarizing film 106 a is reflected by the reflective polarizing film 106 b and enters the region B of the reflective liquid crystal panel 130 .

[0084] The light incident on area A of the reflective liquid crystal panel 130 is reflected by the reflective liquid crystal panel 130 and modulated into linearly polarized light vibrating in the y'z' plane, then passes through the PBS 100 again and enters the diffuser plate 12 via the imaging optical system 11.

[0085] The light incident on region B of the reflective liquid crystal panel 130 is reflected by the reflective liquid crystal panel 130 and modulated into linearly polarized light oscillating in the x'-axis direction. It then passes through the phase difference film (1 / 2λ) 105 and is converted into linearly polarized light oscillating in the y'z'-plane direction, and enters the diffuser plate 12 via the imaging optical system 11.

[0086] According to the fifth embodiment, the orthogonal linearly polarized light beams separated by the reflective polarizing film 106a are guided to the LCOS 130 via different optical paths, and the range of incidence of the light entering the LCOS 130 varies depending on the optical path. Furthermore, the linearly polarized light beams oscillating in the y'z' plane that have passed through the reflective polarizing film 106a are converted by the retardation film (½λ) 105 into linearly polarized light beams oscillating in the x'-axis direction, and are then used as light for forming an image. In other words, by providing the PGU 10 with an optical path in which both of the orthogonal linearly polarized light beams separated by the reflective polarizing film 106a are used for image generation, the utilization efficiency of the light emitted from the light source device 110 can be improved. Furthermore, the length of the PBS 100 in the z'-axis direction can be approximately half the length of the LCOS 130 in the y'-axis direction, thereby enabling the PBS 100 and the illumination optical system 11 to be miniaturized, and thus the entire PGU 10 to be miniaturized. Although not shown, the configuration of Example 5 can also be configured so that the optical axis of the light source of light source device 110 is parallel to the x'-axis, similar to the relationship between Examples 1 and 2. In this case, the length of PBS 100 in the z'-axis direction is half the length of LCOS 130 in the x'-axis direction, and areas A and B, which are the incidence ranges on LCOS 130, are in a line-symmetric relationship with respect to a line parallel to the y'-axis.

[0087] Furthermore, since the difference in the optical paths between area A and area B is smaller than in Example 1, the difference in the illumination range is small, and the difference in brightness and color between area A and area B can be reduced.

[0088] Furthermore, since the PGU 10 is manufactured by attaching the reflective polarizing films 106a and 106b and the retardation film (½λ) 105 to the glass plates 107a and 107b, it can be manufactured easily. [Example 6] Fig. 10A is a diagram showing an example of the configuration of the PGU 10 of Example 6.

[0089] 10A, the PGU 10 includes light source devices 110a and 110b, illumination optical systems 120a and 120b, polarization conversion elements 140a and 140b, a PBS (polarization separation element) 100, and a reflective liquid crystal panel (LCOS) 130. The PBS 100 includes glass plates 101a, 101b, and 101c, and polarization separation films 102a and 102b.

[0090] The polarization separation film 102a is provided between the glass 101a and the glass 101b, and the polarization separation film 102b is provided between the glass 101b and the glass 101c. The polarization separation films are, for example, dielectric multilayer films in which dielectrics with high refractive indexes and dielectrics with low refractive indexes are alternately stacked.

[0091] The polarization conversion elements 140a and 140b convert the light into the same polarization.

[0092] FIG. 10B is a diagram showing an example of the configuration of the polarization conversion element 140a of the sixth embodiment.

[0093] 10B , the polarization conversion element 140a includes glass plates 101d, 101e, and 101f, polarization separation films 102c and 102d, and a retardation film (½λ) 105. The polarization separation film 102c is provided on one of the surfaces between the glass plates 101d and 101e, and the polarization separation film 102d is provided on one of the surfaces between the glass plates 101e and 101f. The retardation film (½λ) 105 is provided on the glass plate 101d.

[0094] Of the light incident on polarization splitting film 102c, linearly polarized light (S-polarized light) vibrating in the x'-axis direction in Fig. 10B is reflected by polarization splitting film 102c and then reflected by polarization splitting film 102d. On the other hand, of the light incident on polarization splitting film 102c, linearly polarized light (P-polarized light) vibrating in the y'z'-plane direction in Fig. 10B passes through polarization splitting film 102c and then through retardation film (½λ) 105, where it is converted into linearly polarized light (S-polarized light) vibrating in the x'-axis direction.

[0095] As a result, the randomly polarized light incident on the polarization conversion element 140a is converted into linearly polarized light (S-polarized light) vibrating in the x'-axis direction and emitted.

[0096] Returning to FIG. 10A, the light from the polarization conversion elements 140a and 140b is reflected by the polarization separation films 102a and 102b, and enters the regions A and B of the reflective liquid crystal panel 130, respectively.

[0097] The light incident on areas A and B of the reflective liquid crystal panel 130 is reflected by the reflective liquid crystal panel 130 and converted into linearly polarized light (P-polarized light) vibrating in the y'z' plane, then passes through the PBS 100 again and enters the diffuser plate 12 via the imaging optical system 11.

[0098] According to the sixth embodiment, the light converted from randomly polarized light to linearly polarized light by the polarization conversion elements 140a and 140b is reflected by the polarization separation films 102a and 102b and enters the regions A and B of the reflective liquid crystal panel 130, respectively, thereby improving the light utilization efficiency of the light source devices 110a and 110b. Furthermore, the lengths of the PBS 100 and the polarization conversion elements 140a and 140b in the z'-axis direction can be approximately half the length of the LCOS 130 in the y'-axis direction, thereby enabling the miniaturization of the PBS 100, the polarization conversion elements 140a and 140b, and the illumination optical system 11, and thus the overall size of the PGU 10. Although not shown, similar to the relationship between the first and second embodiments, even with the configuration of the sixth embodiment, the light sources 110a and 110b can be arranged so that the optical axes of the light sources 110a and 110b are parallel to the x'-axis. In this case, the length in the z'-axis direction of the PBS 100 and the polarization conversion elements 140a and 140b is half the length in the x'-axis direction of the LCOS 130, and the areas A and B, which are the incident ranges on the LCOS 130, are in a line-symmetric relationship with respect to a line parallel to the y'-axis.

[0099] Furthermore, since the optical path lengths of the regions A and B are substantially equal, it is possible to substantially eliminate the difference in brightness and color between the regions A and B. Seventh Embodiment Fig. 11 is a diagram showing an example of the configuration of a PGU 10 according to a seventh embodiment.

[0100] Example 7 differs from Example 1 in that a partition 150 is provided between area A and area B of the LCOS 130. Specifically, the partition 150 has a height in the optical axis direction of the LCOS 130, and is provided at the boundary of the divided light incidence range on the LCOS 130. In other words, the height of the partition 150 is the distance from the LCOS 130 to the PBS 100, and may be shorter than the distance from the LCOS 130 to the PBS 100. Furthermore, the partition in this example is a light-shielding plate, and is not limited to a light-shielding plate, and may be something like a plate.

[0101] In the boundary region between region A and region B of LCOS 130, light from different optical paths mixes, which may cause differences in resolution and color depending on the location in the virtual image displayed in display region 5. In Figure 11, partition 150 separates the light irradiated to region A and region B, thereby preventing differences in resolution and color depending on the location in the virtual image displayed in display region 5.

[0102] According to the seventh embodiment, the light transmitted through the polarization separation film 102a is reflected by the mirror 104, has its polarization direction converted by the retardation film (¼λ) 103, and is made incident on the LCOS 130, thereby improving the light utilization efficiency of the light source device 110. Furthermore, the length of the PBS 100 in the z'-axis direction can be set to approximately half the length of the LCOS 130 in the y'-axis direction, thereby making it possible to miniaturize the PBS 100 and the illumination optical system 11, and thereby miniaturizing the entire PGU 10.

[0103] Furthermore, since the partition 150 is provided between the area A and the area B of the LCOS 130, it is possible to prevent differences in resolution and color depending on the location of the virtual image displayed in the display area 5. [Embodiment 8] Fig. 12 is a diagram showing an example of the configuration of the PGU 10 of embodiment 8.

[0104] The eighth embodiment differs from the first embodiment in that the relative positions of the LCOS 130 a in the area A and the LCOS 130 b in the area B can be adjusted in the optical axis direction of the LCOS 130 .

[0105] The light irradiated onto area A of the LCOS 130 and the light incident onto area B have different optical paths that pass through the PBS 100. Therefore, when divergent light enters the PBS 100, the light that enters area B is incident over a wider range than the light that enters area A. In other words, part of the light that enters area B ends up entering area A, resulting in differences in brightness and color between area A and area B. In addition, differences in brightness and color between area A and area B also occur due to differences in the materials through which the light passes.

[0106] 12, the LCOS 130 has an LCOS 130a in an area A and an LCOS 130b in an area B. The LCOS 130a and the LCOS 130b adjust the brightness and color of each other, thereby reducing the difference in brightness and color between the areas A and B.

[0107] In addition, by adjusting the positions of LCOS 130a and LCOS 130b in the direction (z' axis) in which light reflected by LCOS 130 is emitted so that the difference in optical path length between light incident on area A and light incident on area B is small, the difference in brightness and color between area A and area B is reduced.

[0108] According to the eighth embodiment, the light transmitted through the polarization separation film 102a is reflected by the mirror 104, has its polarization direction converted by the retardation film (¼λ) 103, and is made incident on the LCOS 130, thereby improving the light utilization efficiency of the light source device 110. Furthermore, the length of the PBS 100 in the z'-axis direction can be set to approximately half the length of the LCOS 130 in the y'-axis direction, thereby making it possible to miniaturize the PBS 100 and the illumination optical system 11, and thereby miniaturizing the entire PGU 10.

[0109] Furthermore, since the LCOS 130 has the LCOS 130a in the area A and the LCOS 130b in the area B, the difference in brightness and color between the areas A and B can be reduced.

[0110] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0111] REFERENCE SIGNS LIST 1 Head-up display (HUD) device 2 Vehicle 5 Display area 10 Image forming unit (PGU) 100 Polarization separation element (PBS) 110 Light source device 130 Display panel (reflective liquid crystal panel)

Claims

1. A head-up display device comprising: an image forming unit that emits image light; an imaging optical system that forms the image generated by the image forming unit as a real image on an intermediate screen; and an image projection unit that reflects the image light of the real image formed by the imaging optical system and projects the reflected image light onto a projection member, wherein the image forming unit has: a light source that emits light; a display panel that generates the image; and an optical element that separates the light emitted from the light source into multiple optical paths and guides it to the display panel.

2. A head-up display device according to claim 1, wherein an incident area of ​​light on said display panel is divided according to said plurality of optical paths.

3. A head-up display device according to claim 1, wherein the optical element comprises: a polarizing element which converts the light emitted from the light source into linearly polarized light and emits it from the image forming unit, transmitting one of the mutually orthogonal linearly polarized lights and reflecting the other; and a first retardation film which rotates the polarization axis of the linearly polarized light transmitted through or reflected by the polarizing element by 90°.

4. A head-up display device according to claim 3, wherein the polarizing element has a transparent member and a polarized light separation film, the transparent member is a glass prism or a glass plate, and the polarized light separation film is a reflective polarizing film or a dielectric multilayer film.

5. A head-up display device according to claim 4, wherein the polarizing element is formed by bonding a plurality of the glass prisms together, and the polarized light separation film is disposed on the bonding surfaces of the glass prisms.

6. A head-up display device according to claim 4, wherein the polarizing element includes a plurality of the glass plates, and the polarized light separation film is attached to the joint surfaces of the plurality of glass plates.

7. A head-up display device as described in claim 3, wherein the optical element comprises a second retardation film on the output side of the image forming unit, separate from the first retardation film, and the linearly polarized light output from the image forming unit is converted into circularly polarized light or randomly polarized light by the second retardation film, and is made to enter the image projection unit.

8. A head-up display device according to claim 1, wherein the length of the optical element in the optical axis direction of the display panel is approximately half the length of any one of the four sides constituting the exit surface of the display panel.

9. A head-up display device according to claim 2, wherein a partition having a height in the direction of the optical axis of the display panel is provided at the boundary of the divided light incidence range on the display panel.

10. A head-up display device as described in claim 2, comprising a plurality of display panels corresponding to the plurality of optical paths, and the relative positions of the plurality of display panels in the optical axis direction can be adjusted so that the optical path lengths in the plurality of optical paths are equal.

11. A vehicle comprising a vehicle body and a head-up display device that displays a virtual image in front of the vehicle's windshield or combiner, the head-up display device comprising: an image forming unit that emits image light; an imaging optical system that forms an image generated by the image forming unit as a real image on an intermediate screen; and an image projection unit that reflects the image light of the real image formed by the imaging optical system and projects the reflected image light to a projection member arranged on the vehicle, the image forming unit having a light source that emits light; a display panel that generates the image; and an optical element that separates the light emitted from the light source into multiple optical paths and guides it to the display panel.

12. A vehicle according to claim 11, wherein an incident range of light on said display panel is divided according to said plurality of optical paths.

13. A vehicle as described in claim 11, wherein the optical element has a polarizing element that transmits one of the mutually orthogonal linearly polarized light beams and reflects the other, and a phase difference film that rotates the polarization axis of the linearly polarized light beam transmitted through or reflected by the polarizing element by 90 degrees.

14. A vehicle as described in claim 13, further comprising a second retardation film on the output side of the image forming unit in addition to the retardation film, and the linearly polarized light output from the image forming unit is converted by the second retardation film into circularly polarized light or randomly polarized light, and is then incident on the image projection unit.

15. A vehicle as claimed in claim 11, wherein the length of said optical element in the optical axis direction of said display panel is approximately half the length of any one of the four sides constituting the exit surface of said display panel.

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