Head-up display device, head-up display system, retardation film and laminated glass for vehicles

Abstract

A polarizing part (81) is provided between a video unit (31) for radiating projection light (60) and a projection part (laminated glass 10 for a vehicle) on which projection light (61) is projected. The polarizing part (81) transmits light that oscillates in a specific direction and that is included in the projection light (60), and the projection light (61) transmitted through the polarizing part (81) is projected to the projection part. The specific direction in which the projection light (60) is transmitted in the polarizing part (81) is parallel to an incidence plane. In this case, the present invention can be used as a P-HUD-type head-up display device. By adjusting the oscillation direction of the light transmitted by the polarizing part, the occurrence of a double image can be suppressed when an observer views an image displayed in a region near the outer periphery of a windshield surface or the central region of the windshield surface from an angle.

Description

[Technical field]

[0001] The present disclosure relates to a head-up display device, a head-up display system, a retardation film, and a laminated glass for a vehicle. [Background technology]

[0002] A windshield installed at the front of a vehicle is used as a projection unit for a head-up display (hereinafter sometimes referred to as HUD). The occupant visually recognizes a virtual image based on a reflected image of projected light from the projection unit. In the projection unit, reflected images can be formed on both the interior main surface and the exterior main surface.

[0003] The formation of reflected images on both the interior and exterior principal surfaces of the projection unit leads to a virtual image that can be visually recognized by the occupants as a double image (for the mechanism of double image generation, see Non-Patent Document 1). Methods for suppressing double images in HUD devices include a wedge HUD method and a polarized HUD method.

[0004] In the wedge HUD method, the projection unit is provided with a wedge angle profile whose thickness gradually varies, and the optical path of the projected light is adjusted so that the virtual image based on the reflected image formed on the main surface inside the vehicle, as seen by the occupant, coincides with the virtual image based on the reflected image formed on the main surface outside the vehicle (for the mechanism for suppressing double images, see non-patent document 1).

[0005] Patent Document 1 discloses a polarized HUD type HUD device. In the polarized HUD system, the passenger visually sees a virtual image based on the reflected image of S-polarized or P-polarized projected light from the projection unit. Here, S-polarized light refers to projected light whose vibration direction is perpendicular to the incident plane, while P-polarized light refers to projected light whose vibration direction is parallel to the incident plane.

[0006] In this HUD device, double images of reflected images, i.e. double images of virtual images, are suppressed by the following mechanism. The projection unit comprises a first glass plate arranged on the outside of the room, a second glass plate arranged on the inside of the room, and a retardation film arranged between the first and second glass plates, and the materials of the laminated members are adjusted so that their refractive indices in the visible light range are equal. Then, the projection light containing the aforementioned S-polarized or P-polarized light is incident on the projection unit at the Brewster angle.

[0007] When the incident projection light is S-polarized light, a reflected image is formed on the interior-side principal surface of the second glass plate. The projection light passing through the projection unit becomes P-polarized light due to the retardation film. When the P-polarized light reaches the exterior-side principal surface of the first glass plate, it is emitted to the outside of the vehicle without being reflected by the principal surface. The occupant visually recognizes a virtual image display based on the reflected image of S-polarized light formed on the interior-side principal surface of the second glass plate. This case is referred to as an S-HUD.

[0008] Furthermore, when the incident projection light is P-polarized, the proportion of the projection light reflected by the interior principal surface of the second glass plate is low. The projection light passing through the projection unit becomes S-polarized light due to the retardation film. When the S-polarized light reaches the exterior principal surface of the first glass plate, a portion of it is reflected by the principal surface, and the remainder is emitted from the exterior. The projection light that formed this reflected image passes through the retardation film of the projection unit again, and is changed to P-polarized light. The occupant visually recognizes a virtual image displayed by P-polarized light based on the reflected image formed on the exterior principal surface of the first glass plate. This case is referred to as a P-HUD. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2019 / 244619 [Patent Document 2] JP 2000-249966 A [Non-patent literature]

[0010] [Non-Patent Document 1] "Development of a New Active Driving Display", Mazda Techniques, No. 33 (2016), pp. 60-65 Summary of the Invention [Problem to be solved by the invention]

[0011] In recent years, there has been a demand for diversifying the information displayed by HUD devices. For example, applications include displaying information marked with signs and pedestrians to assist driving. There is also a demand for sharing image information between the driver's seat and the passenger seat. Examples of information to be shared include information displayed by car navigation systems and weather information.

[0012] Thus, in order to meet the need to diversify the information displayed by a HUD device, it may not be sufficient to display information only in front of the driver; it may be necessary to display information in areas other than in front of the driver, such as an area closer to the outer periphery of the windshield surface than in front of the driver, or in the area between the passenger seat and the driver.

[0013] When displaying a virtual image in a polarized HUD system as in Patent Document 1, the occurrence of double images is suppressed by adjusting the angle between the optical axis of the retardation film and the vibration direction of the projection light, keeping in mind that the image is displayed in front of the viewer, who is the passenger viewing the information through the HUD.

[0014] Patent Document 2 lists as a problem that when attempting to display a large area using the polarized HUD method, it becomes difficult to make the display light incident on the entire display area at the Brewster angle, making it impossible to display a large area. It is also described that the deviation of the Brewster angle that accompanies an increase in area can be solved by changing the wedge angle.

[0015] Patent Document 2 describes that the thickness of the front laminated glass is reduced from the position where the optical rotator film is inserted toward the lower side, and the change in thickness is adjusted by the thickness of the optical rotator film to be inserted. It is also described that this method makes it possible to expand the display area by displaying a reflected image at the portion where the optical rotator film is inserted and below it.

[0016] However, the enlargement of the display area by this method is limited to the portion where the polarization rotator film is inserted and below it, and is limited to a method of enlarging the display area in the vertical direction of the windshield surface. Furthermore, reducing the thickness of the front laminated glass in the lower side direction has the disadvantage of increasing the amount of work required in the manufacturing process.

[0017] When passengers are seated in the driver's seat and passenger's seat of a moving vehicle and an image is displayed by the HUD in the central area of ​​the windshield surface, the display area of ​​the image is diagonally viewed from both passengers (viewers). In such a case, even if the head-up display device is designed to suppress the occurrence of double images for the image displayed in front of each viewer using the polarized HUD method, each viewer will see an image at an angle, and both viewers may perceive the image as a double image.

[0018] In consideration of the above, the present disclosure provides a head-up display device that can suppress the occurrence of double images when a viewer views an image displayed in an area near the outer periphery of the windshield surface or in the central area of ​​the windshield surface from an oblique angle. [Means for solving the problem]

[0019] A head-up display device according to a first aspect of a first embodiment of the present disclosure is a head-up display device that is mounted on a moving body and causes a viewer, who is an occupant of the moving body, to recognize a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display device is an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit, for transmitting light that is included in the projection light and that vibrates in a specific direction; the projection unit onto which the projection light transmitted through the polarizing unit is projected; the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front region that is in front of the viewer, and a viewer diagonally forward region that is a region that is farther away than the viewer front region along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer sees the projection unit is 0° and the plane along the retardation film is the projection plane, The retardation film is aligned at an angle of θ r a tilted optical axis that changes the vibration direction of the projection light incident on the projection surface; The specific direction is a direction parallel to the incident surface.

[0020] In a head-up display device according to a first aspect of a first embodiment of the present disclosure, a polarization unit is provided between an imaging unit that irradiates projection light and a projection unit onto which the projection light is projected. The polarizing section transmits light that is contained in the projection light and vibrates in a specific direction, and the projection light that has transmitted through the polarizing section is projected onto the projection section. The specific direction in which the projection light is transmitted through the polarizing section is parallel to the incident surface. In this case, it can be used as a P-HUD type head-up display device. This head-up display device is suitable for use in a sunglasses mode using polarized sunglasses. By adjusting the vibration direction of the light transmitted by the polarizing section, the occurrence of double images can be suppressed when a viewer views an image displayed in an area near the outer periphery of the windshield surface or in the central area of ​​the windshield surface from an oblique angle.

[0021] In addition, in the head-up display device according to the first aspect of the first embodiment of the present disclosure, it is preferable that the viewer observes a virtual image based on a reflected image formed on a surface other than the interior side of the second glass plate. In the head-up display device of the present disclosure, it is preferable that the viewer observes a virtual image based on a reflected image formed on the exterior side surface of the first glass plate.

[0022] A head-up display device according to a second aspect of the first embodiment of the present disclosure is a head-up display device mounted on a moving body, and configured to cause a viewer, who is an occupant of the moving body, to recognize a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display device is an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit, for transmitting light that is included in the projection light and that vibrates in a specific direction; the projection unit onto which the projection light transmitted through the polarizing unit is projected; the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front region that is in front of the viewer, and a viewer diagonally forward region that is a region that is farther away than the viewer front region along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer sees the projection unit is 0° and the plane along the retardation film is the projection plane, The retardation film is aligned at an angle of θ r The projection light has an inclined optical axis and is incident on the projection surface in a vibration direction θ α and the optical axis is defined as dθ, the vibration direction of the incident projection light is rotated by 2dθ, The vibration direction θ α The angle of the incident plane with respect to the X-axis on the projection plane is θ p In this case, 2θ r -θ p It is characterized in that the direction is

[0023] In the head-up display device according to the second aspect of the first embodiment of the present disclosure, the vibration direction of the projection light incident on the projection surface is set to θ α The angle at which the optical axis of the retardation film is inclined with respect to the X axis is θ r The angle of the incident plane with respect to the X-axis on the projection plane is θ p In this case, the vibration direction θ α is 2θ on the above projection plane. r -θ p This is the direction. If the vibration direction of the projection light incident on the projection surface satisfies the above conditions, it can be used as an S-HUD type head-up display device. S-HUD type head-up display devices can display images clearly because the image does not become distorted in rainy weather as with P-HUD type head-up display devices. In addition, when projecting in an oblique direction, for example, θ r 2θ at 45° r -θ p The direction of is not perpendicular to the plane of incidence.

[0024] In the head-up display device according to the second aspect of the first embodiment of the present disclosure, it is preferable that the viewer observes a virtual image based on a reflected image formed on the interior side of the second glass plate.

[0025] In the head-up display device according to the first embodiment of the present disclosure, it is preferable that there are multiple viewers, and for each viewer, the polarizing unit is provided between the image unit and the projection unit, with each entrance surface being an entrance surface provided for each viewer, and each of the polarizing units transmits projection light vibrating in the specific direction corresponding to each entrance surface. It is also preferable that the polarizing sections have transmission axes along which the vibration direction of the transmitted projection light is the specific direction, and that the directions of the transmission axes differ from one another. It is also preferable that the projection light is projected onto a central region that is between the viewer front regions of each of the multiple viewers and corresponds to the viewer diagonally forward region of each of the multiple viewers.

[0026] A polarizing section is provided for each of the multiple viewers, and the vibration direction of the projection light transmitted through the polarizing section is adjusted according to the positional relationship between the incident surface and the projection surface provided for each viewer. This makes it possible to provide a head-up display device that can suppress the occurrence of double images for any viewer when multiple viewers view an image displayed in the central area of ​​the windshield surface from an oblique angle.

[0027] In the head-up display device according to the first embodiment of the present disclosure, the projection position at which the projection light is projected is changeable in the projection unit, It is preferable that the polarizing section is movable so that the vibration direction of the light transmitted through the polarizing section can be changed in response to a change in the plane of incidence accompanying a change in the projection position. When the projection position is changed, the plane of incidence is also changed. If the polarizing section can move in response to the change in the plane of incidence, and the vibration direction of the light passing through the polarizing section can be changed, it is possible to suppress double images even when the projection position is changed.

[0028] A head-up display system according to a first embodiment of the present disclosure is a head-up display system that is mounted on a moving body and allows a viewer, who is an occupant of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display system includes: an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit, for transmitting light that is included in the projection light and that vibrates in a specific direction; The projection unit onto which the projection light is projected, the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front region that is in front of the viewer, and a viewer diagonally forward region that is a region that is farther away than the viewer front region along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer sees the projection unit is 0° and the plane along the retardation film is the projection plane, The retardation film is aligned at an angle of θ r a tilted optical axis that changes the vibration direction of the projection light incident on the projection surface; The polarizing section is movable, and is capable of switching between the following (A) and (B) by changing the vibration direction of light transmitted through the polarizing section. (A) The vibration direction of light incident on the second glass plate is set to be parallel to the incident surface. (B) The phase difference film is a vibration direction θ of the projection light incident on the projection surface.α The angle between the incident surface and the optical axis is dθ, and the vibration direction of the projection light is rotated by 2dθ. The vibration direction of the light transmitted through the second glass plate is defined as the angle of the incident surface with respect to the X-axis on the projection surface by θ. p In this case, 2θ r -θ p The direction should be as follows.

[0029] In the head-up display system according to the first embodiment of the present disclosure, the polarizing unit is movable, and the vibration direction of the light passing through the polarizing unit can be changed, thereby making it possible to switch between the S-HUD method and the P-HUD method. This makes it possible to provide a head-up display system equipped with a plurality of types of double image suppression methods.

[0030] In the head-up display system according to the first embodiment of the present disclosure, the projection position at which the projection light is projected is changeable in the projection unit, It is preferable that the polarizing section is movable so that the vibration direction of the projection light passing through the polarizing section can be changed in response to a change in the plane of incidence accompanying a change in the projection position. When the projection position is changed, the plane of incidence is also changed. If the polarizing section can move in response to the change in the plane of incidence, and the vibration direction of the projection light passing through the polarizing section can be changed, it is possible to suppress double images even when the projection position is changed.

[0031] A head-up display device according to a first aspect of a second embodiment of the present disclosure, A head-up display device is mounted on a moving body, and allows a viewer, who is a passenger of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, the head-up display device comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display device is an imaging unit that irradiates the projection light whose vibration direction is the X-axis direction; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, The second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite to the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction parallel to the incidence surface, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film disposed in the region obliquely forward of the viewer has an optical axis inclined in a direction deviated from 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, The virtual image is based on a reflected image formed on the fourth main surface of the second glass plate, The present invention is characterized in that in both the viewer's front area and the viewer's diagonally forward area, the light emitted from the first main surface of the first glass plate is the projection light that mainly vibrates in a direction parallel to the incident surface.

[0032] In the description of the second embodiment of the present disclosure, the length of the line along the Y axis connecting the viewer's viewpoint and the projection unit (the distance from the viewpoint to the projection unit) is set to 1000 mm, and the line along the Y axis is set to 0°, and the range of ±10° along the X-axis direction is defined as the viewer's front area. An area away from the viewer's front area along any direction in the X-axis direction is defined as an obliquely forward area of ​​the viewer.

[0033] In a head-up display device according to a first aspect of the second embodiment of the present disclosure, when a reflected image formed in a viewer's front area, which is in front of the viewer, is viewed, the optical axis of the retardation film is at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. In the viewer's front area, the projected light is almost entirely S-polarized. In the viewer's front area, the projected light (S-polarized) incident on the retardation film is converted into P-polarized light with high efficiency, thereby suppressing the occurrence of double images.

[0034] When a reflected image formed in a region diagonally forward of the viewer, which is a region away from the viewer's front region, is viewed along any direction in the X-axis direction, the optical axis of the retardation film is inclined in a direction deviated from 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. By tilting the optical axis of the retardation film away from the X-axis by 45°±5°, the ratio of light that vibrates parallel to the plane of incidence of the projected light that passes through the retardation film is increased in response to changes in the plane of incidence of the projected light. As a result, the efficiency of converting the projected light that enters the retardation film into P-polarized light is increased even in the area diagonally forward of the viewer, suppressing the occurrence of double images. The projection light incident on the retardation film is converted into P-polarized light with high efficiency in both the area in front of the viewer and the area obliquely in front of the viewer, so that the occurrence of double images is suppressed. As a result, it is possible to provide a head-up display device that can suppress the occurrence of double images even when the display area of ​​the HUD is expanded in the lateral direction of the windshield surface.

[0035] A head-up display device according to a second aspect of the second embodiment of the present disclosure is a head-up display device mounted on a moving body, and configured to cause a viewer, who is an occupant of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, the head-up display device comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display device is An imaging unit that irradiates the projection light whose vibration direction is parallel to the YZ plane; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, The second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite to the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction perpendicular to the incidence plane, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film disposed in the region obliquely forward of the viewer has an optical axis inclined in a direction deviated from 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, The virtual image is based on a reflected image formed on the first main surface of the first glass plate, The present invention is characterized in that in both the viewer's front area and the viewer's diagonally forward area, the light reflected by the first main surface of the first glass plate is the projection light that mainly vibrates in a direction perpendicular to the incident surface.

[0036] This head-up display device can also be used in a sunglasses mode using polarized sunglasses. In this head-up display device, when a reflected image formed in the viewer's front area, which is in front of the viewer, is viewed, the optical axis of the retardation film is at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. In the viewer's front area, the projected light is almost entirely P-polarized. In the viewer's front area, the projected light (P-polarized) incident on the retardation film is converted to S-polarized light with high efficiency, so the virtual image display based on the reflected image formed on the first principal surface of the first glass plate becomes stronger. Therefore, the influence of the projected light reflected by the fourth principal surface is relatively weak, and the occurrence of double images is suppressed.

[0037] When a reflected image formed in a region diagonally forward of the viewer, which is a region away from the viewer's front region, is viewed along any direction in the X-axis direction, the optical axis of the retardation film is inclined in a direction deviated from 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. By tilting the optical axis direction of the retardation film in a direction deviated from 45°±5° with respect to the X-axis, the proportion of light that vibrates perpendicularly to the incident plane among the light that passes through the retardation film is increased in response to the change in the incident plane of the projection light. As a result, the virtual image display based on the reflected image formed on the first main surface of the first glass plate becomes stronger even in the area diagonally forward of the viewer. Therefore, the influence of the projected light reflected by the fourth main surface is relatively weakened, and the occurrence of double images is suppressed. In both the area in front of the viewer and the area diagonally forward of the viewer, the efficiency of converting the projected light that is incident on the retardation film into S-polarized light is increased, and the occurrence of double images is suppressed. As a result, it is possible to provide a head-up display device that can suppress the occurrence of double images even when the display area of ​​the HUD is expanded in the lateral direction of the windshield surface.

[0038] In the head-up display device according to the second embodiment of the present disclosure, in the region diagonally forward of the viewer, it is preferable that the direction in which the optical axis of the retardation film deviates from 45°±5° with respect to the X-axis is opposite in a right peripheral region located to the right of the viewer's front area and a left peripheral region located to the left of the viewer's front area. By defining it in this way, it is possible to prevent the occurrence of double images on both the left and right sides of the viewer.

[0039] In the head-up display device according to the second embodiment of the present disclosure, it is preferable that the inclination of the direction of the optical axis of the retardation film in the region diagonally forward of the viewer changes continuously along the X-axis direction. It is also preferable that the change in the inclination of the direction of the optical axis of the retardation film in the region obliquely forward of the viewer is discontinuous along the X-axis direction.

[0040] Further, the retardation film according to the second embodiment of the present disclosure is a retardation film which is an integral body having a vertical axis in the up-down direction and a horizontal axis in the left-right direction, At a plurality of points along the vertical axis, an angle between the optical axis of the retardation film and the horizontal axis is constant; The angle between the optical axis of the retardation film and the horizontal axis changes at a constant rate along the horizontal axis.

[0041] By arranging such a retardation film so that the horizontal direction of the retardation film is aligned with the horizontal direction of the windshield, it is possible to provide a HUD device having a wide display area in the horizontal direction of the windshield surface.

[0042] In the retardation film according to the second embodiment of the present disclosure, it is preferable that the angle between the optical axis of the retardation film and the horizontal axis changes continuously along the horizontal axis direction. It is also preferable that the angle between the optical axis of the retardation film and the horizontal axis changes discontinuously along the horizontal axis direction.

[0043] A laminated glass for a vehicle according to a second embodiment of the present disclosure is a laminated glass for a vehicle including a first glass plate, a second glass plate, and a retardation film disposed between the first glass plate and the second glass plate, The retardation film is characterized in that it is a retardation film according to a second embodiment of the present disclosure.

[0044] By using such a laminated glass for a vehicle, it is possible to provide a HUD device having a wide display area in the lateral direction of the windshield surface.

[0045] A head-up display system according to a second embodiment of the present disclosure is a head-up display system that is mounted on a moving body and allows a viewer, who is an occupant of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a plane having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident plane, The head-up display system includes: an imaging unit that irradiates the projection light; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, The second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite to the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction parallel to or perpendicular to the incidence surface, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film disposed in the region obliquely forward of the viewer has an optical axis inclined in a direction deviated from 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, the imaging unit can switch between irradiating a first projection light whose vibration direction is in the X-axis direction and a second projection light whose vibration direction is parallel to the YZ plane; When the viewer views a virtual image without using a polarizing plate, the first projection light is irradiated from the image unit, and the virtual image is based on a reflected image formed on the fourth main surface of the second glass plate, and in both the viewer's front area and the viewer's obliquely forward area, the light emitted from the first main surface of the first glass plate is projection light that mainly vibrates in a direction parallel to the incident surface, When the viewer views a virtual image through a polarizing plate, the second projection light is irradiated from the image unit, and the virtual image is based on a reflected image formed on the first main surface of the first glass plate, and in both the viewer's front area and the viewer's diagonally forward area, the light reflected on the first main surface of the first glass plate is projection light that mainly vibrates in a direction perpendicular to the incident surface.

[0046] The head-up display system according to the second embodiment of the present disclosure can be used to switch between a sunglasses mode in which a virtual image is viewed through a polarizing plate such as polarized sunglasses, and a normal mode in which a virtual image is viewed without a polarizing plate, by switching between two types of projection light emitted from the image unit. Furthermore, when the HUD display area is expanded horizontally across the windshield surface, the occurrence of double images can be suppressed in either mode. Effect of the Invention

[0047] According to the present disclosure, it is possible to provide a head-up display device that can suppress the occurrence of double images when a viewer views an image displayed in an area near the outer periphery of the windshield surface or in the central area of ​​the windshield surface from an oblique angle. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 is a top view of a moving object equipped with a HUD device. [Diagram 2] FIG. 2 is a view of a laminated glass for a vehicle used in a HUD device, viewed from the fourth main surface side. [Diagram 3] FIG. 3 is an exploded perspective view that illustrates an example of a laminated glass for vehicles. [Figure 4] FIG. 4 is a schematic diagram showing an overview of a first HUD device according to a first aspect of a first embodiment of the present disclosure and a light path in the device. [Diagram 5] FIG. 5 is a schematic diagram showing an overview of a second HUD device according to a second aspect of the first embodiment of the present disclosure and a light path in the device. [Figure 6] FIG. 6 is a schematic diagram for explaining the vibration direction of light transmitted through a polarizing section in the second HUD device. [Figure 7] FIG. 7 is a diagram illustrating an example of the relationship between the viewer, the position of the projection unit, and the position of the transmission axis of the polarizing unit in the first HUD device. [Figure 8] FIG. 8 is a diagram illustrating an example of the relationship between the viewer, the position of the projection unit, and the position of the transmission axis of the polarizing unit in the second HUD device. [Figure 9] FIG. 9 is a diagram showing a schematic example of the relationship between a plurality of viewers in the first HUD device, the position of the projection unit, and the position of the transmission axis of the polarizing unit. [Figure 10] FIG. 10 is a diagram showing an example of the relationship between a plurality of viewers in the second HUD device, the position of the projection unit, and the position of the transmission axis of the polarizing unit. [Figure 11] FIG. 11 is a schematic diagram showing the layout of the first HUD device used in the examples and comparative examples. [Figure 12] FIG. 12 is a diagram showing a schematic diagram of an experimental system in Example 1. As shown in FIG. [Figure 13] FIG. 13 is a diagram showing a schematic diagram of an experimental system in Comparative Example 1. As shown in FIG. [Figure 14] FIG. 14 is a photograph showing the virtual images visually recognized in Example 1 and Comparative Example 1. [Figure 15] FIG. 15 is a diagram showing a schematic diagram of an experimental system in Example 2. As shown in FIG. [Figure 16] FIG. 16 is a diagram illustrating an experimental system in Comparative Example 2. As shown in FIG. [Figure 17] FIG. 17 is a photograph showing the virtual images visually recognized in Example 2 and Comparative Example 2. [Figure 18] FIG. 18 is a diagram illustrating an example of a retardation film according to the second embodiment of the present disclosure. [Figure 19] FIG. 19 is a diagram illustrating an example of another retardation film according to the second embodiment of the present disclosure. [Figure 20]FIG. 20 is an exploded perspective view illustrating an example of a laminated glass for a vehicle according to the second embodiment of the present disclosure. [Figure 21] FIG. 21 is a schematic diagram showing an overview of a third HUD device according to a first aspect of the second embodiment of the present disclosure and the optical paths in the device. [Figure 22] FIG. 22 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area in a right-hand drive vehicle. [Figure 23] FIG. 23 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area in a left-hand drive vehicle. [Figure 24] FIG. 24 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when the driver of a right-hand drive vehicle is the viewer. [Diagram 25] FIG. 25 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when the driver of a left-hand drive vehicle is the viewer. [Figure 26] FIG. 26 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area when there are two viewers, a driver and a passenger in the front passenger seat. [Figure 27] FIG. 27 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when there are two viewers, a driver and a passenger in the front passenger seat. [Figure 28] FIG. 28 is a diagram showing a schematic view of an aspect in which the projection unit is extended to the side window. [Figure 29] FIG. 29 is a schematic diagram illustrating an overview of a fourth HUD device according to a second aspect of the second embodiment of the present disclosure and the optical paths in the device. [Diagram 30] FIG. 30 is a schematic diagram showing the layout of the third HUD device used in the examples and comparative examples. [Diagram 31] FIG. 31 is a diagram showing a schematic diagram of an experimental system in Example 3. As shown in FIG. [Diagram 32] FIG. 32 is a diagram showing a schematic diagram of an experimental system in Comparative Example 3. As shown in FIG. [Diagram 33]FIG. 33 is a photograph showing the virtual images visually recognized in Example 3 and Comparative Example 3. [Diagram 34] FIG. 34 is a diagram showing a schematic diagram of an experimental system in Example 4. As shown in FIG. [Diagram 35] FIG. 35 is a diagram illustrating an experimental system in Comparative Example 4. As shown in FIG. [Diagram 36] FIG. 36 is a photograph showing the virtual images visually recognized in Example 4 and Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] (First embodiment) A head-up display device (HUD device) and a head-up display system (HUD system) according to a first embodiment of the present disclosure will be described with reference to the drawings.

[0050] The HUD device according to the first embodiment of the present disclosure includes a HUD device in which the viewer observes a virtual image based on a reflected image formed on a surface other than the interior side of the second glass plate (a P-HUD type HUD device), and a HUD device in which the viewer observes a virtual image based on a reflected image formed on the interior side of the second glass plate (an S-HUD type HUD device), and these are also referred to as a first HUD device and a second HUD device, respectively. In the description of the head-up display device according to the first embodiment of the present disclosure, when there is no need to distinguish between the first HUD device and the second HUD device, they are simply referred to as the HUD device according to the first embodiment of the present disclosure. Furthermore, the HUD system according to the first embodiment of the present disclosure is a system that can be used as both a first HUD device and a second HUD device by switching the vibration direction of light that passes through the polarizing section in one system.

[0051] In the description of the first embodiment of the present disclosure, the length of the line along the Y axis (the distance from the viewpoint to the projection unit) among the lines connecting the viewpoint of the viewer and the projection unit is set to 1000 mm, and the range of ±3° along the X axis when the line along the Y axis is set to 0° is defined as the viewer's front area. In addition, when the range is expanded along the Z axis direction, it is also defined as the viewer's front area. The region away from the viewer's front region along any direction in the X-axis direction is defined as the viewer's diagonally forward region. The regions away from the viewer's front region along the X-axis direction and the Z-axis direction are also defined as the viewer's diagonally forward region. In the description of the first embodiment of the present disclosure, a surface along the retardation film and on which projection light is incident on the retardation film is referred to as a projection surface. The projection surface is a surface that includes the main surface of the retardation film.

[0052] [Head-up display device (HUD device)] There are two types of HUD devices according to the first embodiment of the present disclosure: a first HUD device and a second HUD device. First, the definitions of the X-axis, Y-axis, and Z-axis and the moving object, which are common to both HUD devices, will be described. FIG. 1 is a top view of a moving body equipped with a HUD device, and FIG. 2 is a view of a laminated glass for a vehicle used in the HUD device, viewed from the indoor side (fourth main surface) of a second glass plate. The directions of the X-axis, Y-axis, and Z-axis in this disclosure will be described with reference to Figures 1 and 2. Figure 1 shows a vehicle 20 as a moving body, with the X-axis in the horizontal direction and the Y-axis in the vertical direction. The Z-axis is perpendicular to the paper surface. The Y axis is horizontal to the ground and is the direction of travel when the vehicle 20, which is a moving body, moves forward. The X-axis is a direction parallel to the ground and perpendicular to the traveling direction (Y-axis) when the vehicle 20, which is a moving body, moves forward. The Z axis is perpendicular to the ground. Moreover, the direction of the first glass plate when looking from the second glass plate side toward the first glass plate side is defined as the "front".

[0053] Examples of the mobile body include vehicles (passenger cars, trucks, buses, trains, etc.), steam trains, ships, airplanes, etc. Among these, vehicles are preferable.

[0054] 2 shows a laminated glass for vehicles 10. When the laminated glass for vehicles 10 is installed in a vehicle, the glass surface is often not parallel to the XZ plane, but is tilted from the XZ plane.

[0055] Next, the laminated glass for vehicles will be described. FIG. 3 is an exploded perspective view that illustrates an example of a laminated glass for vehicles. The first glass plate has a first main surface exposed to the outside, and a second main surface opposite the first main surface. The second glass plate also has a fourth main surface exposed to the interior side, and a third main surface opposite the fourth main surface. The above-mentioned term "exposed" means that each main surface may have a film, membrane, or the like for imparting various functions such as anti-fogging property, scratch resistance, etc., within a range that does not impair the function of the laminated glass for vehicles. FIG. 3 shows a laminated glass 10 for a vehicle. 3 shows a view in which the second glass plate 12 is disposed on the front side of the drawing, and the surface visible on the front side is the fourth main surface 124. The surface opposite the fourth main surface 124 is the third main surface 123. The first glass plate 11 is disposed at the rear side of the drawing, and the surface seen at the front side is the second main surface 112. The surface opposite the second main surface 112 is the first main surface 111. A retardation film 100 is disposed between the first glass plate 11 and the second glass plate 12 . The fourth main surface 124 is the surface exposed to the interior of the vehicle, and is therefore the surface that is directly viewed by a viewer when the laminated glass for vehicles is installed in a vehicle. That is, Fig. 3 shows the positional relationship in which a viewer directly views the fourth main surface 124 from inside the vehicle.

[0056] In the laminated glass for vehicles, the first glass plate and the second glass plate are preferably bonded together via an interlayer film to form an integral structure. The interlayer film is heated at a temperature at which the polymer constituting the interlayer film softens to laminate the first glass plate and the second glass plate together. Examples of the polymer that can be used include polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), acrylic resin (PMMA), urethane resin, polyethylene terephthalate (PET), and cycloolefin polymer (COP). The interlayer film may be composed of multiple resin layers.

[0057] As the glass material constituting the laminated glass for vehicles, a flat glass plate processed into a curved shape can be suitably used. As the material of the glass plate, a material having a known glass composition such as soda-lime silicate glass as specified in ISO16293-1, aluminosilicate glass, borosilicate glass, non-alkali glass, etc. can be used. The thickness of each of the first glass plate and the second glass plate may be, for example, 0.4 mm to 3 mm. The distance between the first glass plate and the second glass plate may be 0.01 mm to 2.5 mm.

[0058] The retardation film 100 is rotated by an angle θ r It has an inclined optical axis, and changes the vibration direction of the projection light incident on the projection surface by the optical axis. For example, when the retardation film is a half-wavelength film, when the angle between the vibration direction of the projection light incident on the projection surface and the optical axis is dθ, the vibration direction of the incident projection light is rotated by 2dθ. In the first embodiment of the present disclosure, the optical axis of the retardation film means the axis in the direction in which the refractive index of the retardation film is the largest. The retardation film may also include a layer or film that does not have a substrate. For example, a layer having an optical axis in the projection section may be formed by coating, lamination, attachment, adhesion, pressure bonding, transfer, or the like.

[0059] The retardation film is disposed between the first glass plate and the second glass plate. The retardation film may be disposed inside the interlayer, may be disposed in contact with the first glass plate, or may be disposed in contact with the second glass plate. As shown in FIG. 3, the retardation film may be disposed so that its surface faces the second main surface and the third main surface. The retardation film may be disposed over the entire surface or may be disposed partially, and it is preferable that the total area of ​​the surface of the retardation film facing the second main surface or the third main surface is equal to or less than the area of ​​the second main surface or the third main surface. Furthermore, a plurality of retardation films may be used as necessary, and different types of retardation films or films other than retardation films may be used in combination. By arranging the side of the laminated glass for vehicles on which the retardation film is arranged so as to be along the X-axis, the laminated glass for vehicles can be used as a windshield.

[0060] As the retardation film, a retardation element obtained by uniaxially or biaxially stretching a plastic film such as polycarbonate, polyarylate, polyethersulfone, cycloolefin polymer, triacetyl cellulose, polyethylene terephthalate (PET), or polyethylene naphthalate (PEN), or a retardation element obtained by orienting a liquid crystal polymer in a specific direction and fixing the orientation state can be used. The former retardation element obtained by uniaxially or biaxially stretching a plastic film can be produced by, for example, a solvent casting method in which a polymer resin is dissolved in a solvent, applied to a smooth surface such as a stainless steel belt or polyethylene terephthalate (PET), and the film is wound up after the solvent is evaporated, or a melt extrusion method in which a polymer resin is put into an extruder, heated and melted, extruded through a slit (T-die), cooled, and then wound up. A stretching machine is generally used for stretching, and retardation films stretched vertically, horizontally, obliquely, etc. can be obtained. As the latter retardation element, for example, a liquid crystal polymer can be applied onto a transparent substrate such as a transparent plastic film of oriented polyethylene terephthalate (PET) or triacetyl cellulose (TAC), and then heat-treated and cooled to fix the liquid crystal orientation. Examples of the liquid crystal polymer are not particularly limited as long as they are compounds that exhibit liquid crystallinity such as nematic liquid crystal, twisted nematic liquid crystal, discotic liquid crystal, and cholesteric liquid crystal when oriented in a specific direction. For example, those that exhibit twisted nematic orientation in the liquid crystal state and become glassy below the liquid crystal transition point can be used, and examples of such liquid crystal polymers include main chain liquid crystal polymers such as optically active polyester, polyamide, polycarbonate, and polyesterimide, and side chain liquid crystal polymers such as optically active polyacrylate, polymethacrylate, polymerote, and polysiloxane. In addition, examples of such polymer compositions that are not optically active and that contain other low-molecular or high-molecular optically active compounds can be exemplified. The roles of the retardation films in the first HUD device and the second HUD device will be described later.

[0061] [First HUD device] First, a HUD device according to a first aspect of a first embodiment of the present disclosure will be described using a first HUD device as an example. FIG. 4 is a schematic diagram showing an overview of a first HUD device according to a first aspect of a first embodiment of the present disclosure and a light path in the device. In FIG. 4, the optical path of the projection light is shown by a solid line. In the first HUD device 1, the projection portion is a laminated glass 10 for a vehicle shown in FIG.

[0062] In the first HUD device 1 shown in FIG. Here, a plane including three points, namely, light emitting point 32 of image section 31, reflection point 33 where projection light 60 is reflected by first main surface 111, and viewpoint 34 of viewer 35, is the plane of incidence.

[0063] The vibration direction of the projection light 60 emitted from the image unit 31 does not need to be limited, but it is preferable that the light be P-polarized light whose vibration direction is parallel to the plane of incidence, since this increases the amount of light that passes through the polarizing unit 81 and allows a greater amount of light to reach the first principal surface. In a vehicle, the video unit 31 is preferably disposed on the dashboard of the vehicle. By changing the direction in which the projection light 60 is emitted from the image unit 31 or by moving the position of the image unit 31, the position at which the projection light 60 is emitted can be moved.

[0064] A polarizing unit 81 is provided between the image unit 31 and the projection unit (the laminated glass 10 for vehicles). The polarizing unit 81 is a member having a transmission axis that causes the vibration direction of the transmitted projection light 60 to be a specific direction, and for example, a known polarizing plate or the like can be used. The polarizing plate preferably has an absorption axis that absorbs light that vibrates in a direction perpendicular to the specific direction. When the polarizing plate has the transmission axis and the absorption axis, for example, when light that vibrates in a direction not aligned with either the transmission axis or the absorption axis is incident, the vibration direction of the transmitted light can be easily set to the specific direction. The polarizing unit 81 may be disposed in a position where the projection light 60 can pass through the polarizing unit 81 before reaching the projection unit. For example, in a vehicle, the polarizing unit 81 is preferably disposed in the dashboard similarly to the above-described image unit 31, and disposed adjacent to the light source so that the light from the light source quickly passes through the polarizing unit 81.

[0065] In the first HUD device 1, the polarizing section 81 transmits light that vibrates in a direction parallel to the plane of incidence. That is, the projection light 61 that has passed through the polarizing section 81 becomes P-polarized light.

[0066] When the projection light 61 after passing through the polarizing unit 81 is P-polarized, it can also be used in sunglasses mode, where a virtual image is observed through polarized sunglasses. Although polarized sunglasses 36 are used in FIG. 4, the virtual image can of course also be observed with the naked eye. First, the projection light 60 emitted from the image unit 31 passes through the polarizing unit 81 and is irradiated onto the fourth principal surface 124 as P-polarized projection light 61. The angle at this time is preferably Brewster's angle. Generally, P-polarized light incident at the Brewster's angle does not cause reflection, so it is possible to suppress reflection at the fourth principal surface 124, which causes double images. The imaging section can be moved in the X-axis direction and the Y-axis direction so that the angle at which the projection light 61 is irradiated onto the fourth main surface 124 is the Brewster's angle. Next, when the projection light 61 that has traveled through the projection unit is incident on the retardation film 100, the vibration direction is changed. In the first HUD device 1, it is sufficient that reflection occurs on any surface other than the fourth main surface, so that the retardation film 100 can be a ½ wavelength film (half wavelength film), a ¼ wavelength film, or the like. The vibration direction of light after passing through retardation film 100 varies depending on the type of retardation film and the direction of the optical axis. For example, when a half-wavelength film is used as the retardation film, when the angle between the vibration direction of the projection light incident on the projection surface and the optical axis of the retardation film is dθ, the vibration direction of the projection light is rotated by 2dθ. Next, when the projection light reaches first main surface 111, it is reflected to form a reflected image. At this time, S-polarized light is reflected as the reflected light, and the other light that is not reflected passes through first main surface 111 and is emitted to the outside of the room. Next, the reflected image formed on the first principal surface 111 passes through the retardation film 100 again and becomes P-polarized light. The viewer 35 visually recognizes a virtual image 621 on the extension of the optical path 62 based on the reflected image on the first principal surface 111. Since the virtual image 621 is made of P-polarized light, the viewer 35 can view the virtual image 621 even through the polarized sunglasses 36 . In this case, the viewer observes a virtual image based on a reflected image formed on the exterior side (that is, the first main surface) of the first glass plate.

[0067] Furthermore, if there is a reflective layer that reflects light before it reaches first principal surface 111, reflection occurs at that layer. In that case, if the unreflected light reaches first principal surface 111 and is further reflected, this reflection may cause a double image. For this reason, if reflection occurs before it reaches first principal surface 111, it is preferable to change the vibration direction of the light so that it becomes P-polarized again before it reaches first principal surface 111. In this case, it is preferable that the viewer observes a virtual image based on a reflected image formed on a surface other than the indoor surface of the second glass plate. The "reflected image formed on a surface other than the indoor surface of the second glass plate" also includes a "reflected image formed on the outdoor surface of the first glass plate."

[0068] Moreover, in the first HUD device, it is preferable that the polarizing section 81 is movable so that the vibration direction of the light passing through the polarizing section 81 can be changed. If the polarizing unit 81 is movable, when the incident plane changes, the specific direction can be aligned to a direction parallel to the incident plane by moving the polarizing unit 81. By aligning the specific direction to a direction parallel to the incident plane, the device can be suitably used as a P-HUD type HUD device.

[0069] [Second HUD device] Next, a HUD device according to a second aspect of the first embodiment of the present disclosure will be described using a second HUD device as an example. FIG. 5 is a schematic diagram showing an overview of a second HUD device according to a second aspect of the first embodiment of the present disclosure and a light path in the device. In FIG. 5, the optical path of the projection light is shown by a solid line. In the second HUD device 2, the projection portion is the laminated glass 10 for vehicles shown in FIG.

[0070] A polarizing unit 82 is provided between the image unit 31 and the projection unit (vehicle laminated glass 10). The polarizing unit 82 is a member having a transmission axis that transmits light that is included in the projection light and vibrates in a specific direction, and for example, a known polarizing plate or the like can be used. The polarizing unit 82 may be disposed in a position where the projection light 40 can pass through the polarizing unit 82 before reaching the projection unit. For example, in a vehicle, the polarizing unit 82 is preferably disposed in the dashboard similarly to the above-described image unit 31, and disposed adjacent to the light source so that the light from the light source quickly passes through the polarizing unit 82.

[0071] In the second HUD device 2, the polarizing section 82 transmits light that is included in the projection light 40 and vibrates in a specific direction.

[0072] In the second HUD device 2, projection light 40 is emitted from the image section 31. After the projection light 40 passes through the polarizing unit 82, the projection light 41 is irradiated onto the fourth principal surface 124, and a reflected image is formed on the fourth principal surface 124. The viewer 35 observes a virtual image 421 on an extension of the optical path 42 based on the reflected image formed on the fourth principal surface 124.

[0073] A plane including three points, namely, light emitting point 32 of image section 31, reflection point 33 where projection light 41 is reflected by fourth main surface 124, and viewpoint 34 of viewer 35, is the plane of incidence.

[0074] The projection light 40 emitted from the image unit 31 is not particularly limited in terms of the vibration direction of the light, but it is desirable for the light to include light vibrating in a direction parallel to the transmission axis of the polarizing unit 82 in order to increase the amount of light vibrating in a specific direction that passes through the polarizing unit 82. The projection light vibrating in a specific direction becomes a transmitted light that passes through the second glass plate and a reflected light that is reflected on the interior side of the second glass plate. The vibration direction of the projection light vibrating in a specific direction that has passed through the polarizing unit is a vibration direction θ α It becomes.

[0075] In a vehicle, the video unit 31 is preferably located on the dashboard of the vehicle. By changing the direction in which projection light 40 is emitted from image section 31 or by moving the position of image section 31, the position at which projection light 40 is emitted can be moved.

[0076] When a portion of the projection light 41 after passing through the polarizing section 82 passes through the fourth principal surface 124 without being reflected therefrom, the vibration direction of the projection light 41 that has traveled within the projection section changes as a result of passing through the phase difference film 100. The retardation film 100 is angled θ with respect to the X-axis on the projection plane. r The projection light 41 has an inclined optical axis, passes through the second glass plate 12, and is incident on the projection surface in a vibration direction θα The angle of the incident plane with respect to the X-axis on the projection plane is θ p In this case, 2θ r -θ p When the projection light is oriented in this direction, the vibration direction of the projection light is rotated by 2dθ as described above by passing through the retardation film 100, and becomes parallel to the plane of incidence, that is, the same vibration direction as P-polarized light. The change in the vibration direction of the projection light 41 will be described below with reference to the drawings.

[0077] Fig. 6 is a schematic diagram for explaining the vibration direction of light incident on the retardation film 100 in the second HUD device. Fig. 6 also shows the case where the viewer looks forward (in the direction looking from the fourth principal surface side to the first principal surface side). In FIG. 6, the X-axis is shown as 0°. The angle of the optical axis of the retardation film with respect to the X axis is θ r Here, θ r is shown at 45°. The vibration direction of P-polarized light is parallel to the plane of incidence, and the vibration direction of S-polarized light is perpendicular to the plane of incidence. The angle between the vibration direction of the projection light 41 and the optical axis of the retardation film is dθ. When the projection light 41 passes through the retardation film, the vibration direction of the projection light rotates by 2dθ. That is, the vibration direction of the projection light 41 rotates by 2dθ clockwise or counterclockwise in the drawing. This rotation makes the vibration direction of the projection light 41 parallel to the plane of incidence. When such a condition is satisfied, the projection light 41 is changed to P-polarized light by passing through the phase difference film.

[0078] The projection light vibration direction incident on the projection surface that satisfies this condition is defined as θ α Let us put it as follows. θ α is calculated as follows: The angle of the incident surface with respect to the X-axis is θ p The angle is given by: From Figure 6, dθ=θ p -θ r Equation (1) From Fig. 6, θ α =θ r -dθ. Equation (2) From the above formulas (1) and (2), θ α =2θ r -θ p It becomes. When the above formula (1) is +, the vibration direction rotates counterclockwise in FIG. 6, and when it is -, the vibration direction rotates clockwise. That is, θ α =2θ r -θ p When projection light 41 satisfying the above requirement is incident on a retardation film, the vibration direction of the light after passing through the retardation film becomes parallel to the plane of incidence. Before the projection light is incident on the retardation film 100, the vibration direction θ of the projection light is α θ α =2θ r -θ p By satisfying the above condition, light in other vibration directions that causes a double image is prevented from entering the phase difference film.

[0079] The projection light that has passed through the retardation film 100 and become P-polarized light is not reflected by the first main surface 111, and is emitted to the outside as it remains P-polarized light. In this way, if it is possible to prevent the projection light that is not reflected by the fourth principal surface 124 from being reflected by the first principal surface 111, the occurrence of double images can be prevented.

[0080] Moreover, in the second HUD device, it is preferable that the polarizing section 82 is movable so that the vibration direction of the light passing through the polarizing section 82 can be changed. If the polarizing unit 82 is movable, when the plane of incidence changes, the polarizing unit 82 moves, thereby changing the vibration direction of the light transmitted through the polarizing unit 82, and the vibration direction θ of the projection light incident on the projection plane can be changed. α θ α =2θ r -θ p Since the polarizing unit 82 is movable, the vibration direction θ of the projection light incident on the projection surface can be adjusted to a direction that satisfies the above even if the projection position is changed.α θ α =2θ r -θ p Since it is easy to adjust the direction to satisfy the above, it can be suitably used as a HUD device of the S-HUD type.

[0081] [Example of the direction of the transmission axis of the polarizing part] Next, examples of the orientation of the transmission axis of the polarizing unit in each of the first HUD device and the second HUD device will be described. Note that the HUD device of the present disclosure is not limited to the examples given below. In the example below, the viewer is seated in the driver's position in a right-hand drive vehicle. The area in front of the viewer is the viewer's front region, and an area farther away from the viewer's front region along any direction in the X-axis direction is the viewer's diagonally forward region.

[0082] FIG. 7 is a diagram illustrating an example of the relationship between the viewer, the position of the projection unit, and the direction of the transmission axis of the polarizing unit in the first HUD device. In FIG. 7, a viewer 35 is seated in the driver's position in a right-hand drive vehicle. 7 shows an image 621L projected onto an area diagonally forward of the viewer 35 on the left side, and the direction of the transmission axis of a polarizing unit 81L used when viewing the image 621L. Also shown is an image 621R projected onto an area diagonally forward of the viewer 35 on the right side, and the direction of the transmission axis of a polarizing unit 81R used when viewing the image 621R.

[0083] When a viewer views each image, the direction of the transmission axis of the polarizing portion is adjusted. The direction of the transmission axis of the polarizing unit in FIG. 7 is along the Z axis in the area in front of the viewer, and this case is shown by a dotted line in polarizing unit 81L and polarizing unit 81R with this as the reference line. In contrast, the transmission axes of the polarizing section 81L and the polarizing section 81R are indicated by solid lines in the polarizing section 81L and the polarizing section 81R. In the case of Fig. 7, for example, the polarizing unit 81L provided on the left side of the viewer rotates the transmission axis counterclockwise on a plane along the XZ plane. On the other hand, the polarizing unit 81R provided on the right side of the viewer rotates the transmission axis clockwise. The angle at which the transmission axis is rotated may be adjusted to an angle at which double images are reduced to the minimum. In addition, it is preferable to adjust the transmission axis so that it is parallel to the incident surface. In addition, since the transmission axis is on the Z axis in FIG. 7, the direction along the Z axis is used as the reference. However, when the transmission axis is on the X axis as in FIG. 8, the direction along the X axis is used as the reference.

[0084] FIG. 8 is a diagram illustrating an example of the relationship between the viewer, the position of the projection unit, and the direction of the transmission axis of the polarizing unit in the second HUD device. In FIG. 8, a viewer 35 is seated in the driver's position in a right-hand drive vehicle. 8 shows an image 421L projected onto an area diagonally forward of the viewer 35 on the left side, and the direction of the transmission axis of the polarizing unit 82L used when viewing the image 421L. Also shown is an image 421R projected onto an area diagonally forward of the viewer 35 on the right side, and the direction of the transmission axis of the polarizing unit 82R used when viewing the image 421R.

[0085] When a viewer views each image, the direction of the transmission axis of the polarizing portion is adjusted. The direction of the transmission axis of the polarizing unit in FIG. 8 is along the X-axis in the area in front of the viewer, and this case is shown by a dotted line in the polarizing unit 82L and the polarizing unit 82R with this as the reference line. In contrast, the transmission axes of the polarizing section 82L and the polarizing section 82R are indicated by solid lines in the polarizing section 82L and the polarizing section 82R. 8, for example, the polarizing unit 82L provided on the left side of the viewer rotates the transmission axis clockwise on a plane along the XZ plane, while the polarizing unit 82R provided on the right side of the viewer rotates the transmission axis counterclockwise. The angle at which the transmission axis is rotated may be adjusted to an angle at which the double image is reduced to the minimum.

[0086] Although Figs. 7 and 8 show an example in which the optical axis of the retardation film is at 45°, depending on the angle of the optical axis, double images may be further suppressed by rotating the transmission axis in the opposite direction to the above-mentioned direction.

[0087] [Optional form] The HUD device described above is particularly suitable for projecting an image onto the windshield of an automobile, but it is of course also possible to project an image onto the side window of an automobile, etc. When projecting an image onto a side window, a retardation film is placed on the side window, and projection light is irradiated in the same manner as in the case of the windshield, with the direction parallel to the ground and perpendicular to the traveling direction when the moving object moves forward being the Y axis, and the direction parallel to the ground and the traveling direction when the moving object moves forward being the X axis.

[0088] [Example when multiple viewers are present] The HUD device according to the first embodiment of the present disclosure can be a head-up display device that can suppress the occurrence of double images from the perspective of any of a plurality of viewers when the plurality of viewers view an image displayed in the central area of ​​the windshield surface from an oblique angle. The following describes how to prevent the occurrence of double images when there are two viewers: a driver sitting in the driver's position in a right-hand drive vehicle and a passenger sitting in the passenger seat. The area in front of the driver and the passenger is the viewer's front area, and the area farther away from the viewer's front area along any direction in the X-axis direction is the viewer's diagonally forward area. Areas farther away from the viewer's front area along the X-axis direction and the Z-axis direction are also the viewer's diagonally forward area. The projected light is projected onto a central region between the viewer front regions of the driver and the passenger, and corresponding to the viewer diagonally forward regions of the driver and the passenger.

[0089] FIG. 9 is a diagram showing an example of the relationship between a plurality of viewers in the first HUD device, the positions of the projection unit, and the directions of the transmission axes of the polarizing units. In the first HUD device 1 shown in FIG. 9, the viewers, that is, the driver 35D and the passenger 35P, view the image 621C projected in the central area. Although one image 621C is displayed in FIG. 9, a plurality of images may be displayed.

[0090] In FIG. 9, an imaging unit (not shown) is provided for each of the driver 35D and the passenger 35P, and each imaging unit irradiates a projection light onto the projection unit (front glass surface) so that the images 621C overlap in the central region. In a vehicle, it is preferable that a plurality of video units are arranged on the dashboard of the vehicle to accommodate a plurality of viewers. Further, a polarizing unit 81D and a polarizing unit 81P are provided for the driver 35D and the passenger 35P, respectively. The polarizing unit 81D and the polarizing unit 81P are provided between the image unit and the projection unit corresponding to the driver 35D and the passenger 35P, respectively. In a vehicle, the polarization unit 81D and the polarization unit 81P are preferably positioned in the dashboard, like the imaging unit, and are positioned adjacent to the light source so that light from the light source is quickly transmitted through the polarization unit 81D or the polarization unit 81P.

[0091] The polarizing unit 81D has a transmission axis that transmits projection light vibrating in a direction parallel to the incident plane of the driver 35D, and the polarizing unit 81P has a transmission axis that transmits projection light vibrating in a direction parallel to the incident plane of the passenger 35P. The direction of the transmission axis of the polarizing section 81D is different from the direction of the transmission axis of the polarizing section 81P. 9, the direction of the transmission axis of the polarizing unit 81D is along the YZ plane in the region in front of the viewer, and is rotated counterclockwise from this reference line. The direction of the transmission axis of the polarizing unit 81P is along the YZ plane in the region in front of the viewer, and is rotated clockwise from this reference line. The direction of the transmission axis of the polarizing unit 81D and the direction of the transmission axis of the polarizing unit 81P are adjusted according to the relationship between the position of the incident surface and the projection surface provided for each viewer. In this way, when multiple viewers (the driver and passengers) view an image displayed in the central area of ​​the windshield surface from an oblique angle, it is possible to provide a head-up display device that can suppress the occurrence of double images for any viewer.

[0092] FIG. 10 is a diagram showing an example of the relationship between a plurality of viewers in the second HUD device, the position of the projection unit, and the direction of the transmission axis of the polarizing unit. In the second HUD device 2 shown in FIG. 10, the viewers, that is, the driver 35D and the passenger 35P, view the image 421C projected in the central area.

[0093] An entrance surface is provided for each of the driver 35D and the passenger 35P. In addition, polarizing units 82D and 82P are provided for driver 35D and passenger 35P, respectively. The polarizing unit 82D adjusts the angle of the optical axis of the retardation film by θ r The angle of the plane of incidence for the driver 35D with respect to the X-axis on the projection plane is θ p In this case, the vibration direction θ of the projection light that is transmitted through the polarizing unit 82D and incident on the projection surface is α is θ α =2θ r -θ p It is designed to satisfy the following. In addition, the polarizing unit 82P adjusts the angle of the optical axis of the retardation film by θ r The angle of the plane of incidence for the passenger 35P with respect to the X-axis on the projection plane is θ p In this case, the vibration direction θ of the projection light that is transmitted through the polarizing unit 82P and incident on the projection surface is α is θ α =2θ r -θ p It is designed to satisfy the following. The direction of the transmission axis of the polarizing section 82D is different from the direction of the transmission axis of the polarizing section 82P. 10, the direction of the transmission axis of the polarizing unit 82D is along the XY plane in the region in front of the viewer, and is rotated clockwise from this reference line. The direction of the transmission axis of the polarizing unit 82P is along the XY plane in the region in front of the viewer, and is rotated counterclockwise from this reference line. The direction of the transmission axis of the polarizing unit 82D and the direction of the transmission axis of the polarizing unit 82P are adjusted according to the relationship between the position of the incident surface and the projection surface provided for each viewer. In this way, when multiple viewers (the driver and passengers) view an image displayed in the central area of ​​the windshield surface from an oblique angle, it is possible to provide a head-up display device that can suppress the occurrence of double images for any viewer.

[0094] [Head-up display system (HUD system)] The HUD system according to the first embodiment of the present disclosure is a system in which the vibration direction of light passing through a polarizing section can be switched in one system. The system can be used as both a first HUD device and a second HUD device by changing the vibration direction of the light that passes through the polarizing portion. Specifically, the following (A) and (B) can be switched. (A) The vibration direction of light incident on the second glass plate is set to be parallel to the incident surface. (B) The phase difference film is a vibration direction θ of the projection light incident on the projection surface. α The vibration direction of the light transmitted through the second glass plate is rotated by 2dθ when the angle between the incident surface and the optical axis is dθ. The angle of the incident surface with respect to the X-axis on the projection surface is then θ. p In this case, 2θ r -θ p The direction should be as follows. In the case of (A) above, it becomes a P-HUD and can be used as the first HUD device. If you do as in (B) above, it becomes an S-HUD and can be used as a second HUD device.

[0095] Furthermore, in the projection unit, the projection position onto which the projection light is projected may be changeable. In the first HUD device, the polarizing section has a transmission axis that transmits light that vibrates in a particular direction parallel to the plane of incidence. Here, when the projection position is changed, the incidence surface is changed. If the position of the polarizing section remains the same when the plane of incidence is changed, the vibration direction of the light that passes through the polarizing section will shift from a direction parallel to the plane of incidence. As a result, the proportion of light that is not P-polarized after passing through the polarizing section will increase, making it more likely that double images will occur. Therefore, when the projection position is changed, the polarizing section is moved in accordance with the projection position, the vibration direction of the projection light passing through the polarizing section is changed, and the light vibrating in a direction parallel to the changed incidence surface is transmitted. This makes it possible to prevent double images even if the projection position is changed.

[0096] The same is true for the second HUD device, where the polarizing section and the transmission axis are moved in accordance with the change in the projection position and the change in the incident surface. Specifically, the angle of the changed incidence plane with respect to the X-axis on the changed projection plane is defined as θ p In this case, 2θ r -θ p (The angle of the optical axis of the retardation film is θ r ) to transmit light. This makes it possible to prevent double images even if the projection position is changed.

[0097] (Example according to the first embodiment of the present disclosure) An experiment was conducted to compare the occurrence of double images when the vibration direction of light passing through the polarizing section was changed in both the area directly in front of the viewer and the area diagonally in front of the viewer. First, we present the experimental results when the first HUD device was used. Fig. 11 is a schematic diagram of the layout of the first HUD device used in the examples and comparative examples. Fig. 12 is a schematic diagram of the experimental system in Example 1, and Fig. 13 is a schematic diagram of the experimental system in Comparative Example 1.

[0098] A first HUD device was prepared as shown in Fig. 11. The first HUD device 1 has a square projection area of ​​150 mm x 150 mm for the P-HUD method. The optical axis of the retardation film in the first HUD device 1 was set to 45°. As shown in FIG. 11, the image portion 31 is placed horizontally, and the laminated glass for vehicles 10 is disposed in a positional relationship of 57° to the image portion 31 so as to form a Brewster's angle. A polarizing plate serving as the polarizing unit 81 is placed on the image unit 31 , so that the polarizing unit 81 is disposed between the image unit 31 and the laminated glass 10 for vehicles. Projection light is emitted vertically upward from the image unit 31, and a viewer 35 observes a virtual image on the extension of the optical path based on the reflected image on the first main surface 111. The height of the viewer's eye point is the same as the height of the laminated glass for vehicles. A tablet is used as the image unit 31, and a green lattice image is displayed from the tablet. A polarizing plate is placed on the tablet, and the tablet is placed directly under the laminated glass for a vehicle. In order to simulate nighttime driving of a moving object, a black background plate 37 is disposed on the other side of the laminated glass 10 for vehicles in the direction of the viewer 35's view.

[0099] As shown in Figs. 12 and 13, the observation point was set to be a point in front of the viewer 35, which was set as position 0 in the X-axis direction, and points of -200 mm and -400 mm were set to the left of it. The left side of the X-axis is the "-" direction, and the right side is the "+" direction. In the first embodiment, as shown in FIG. 12, in the region in front of the viewer (position 0 in the X-axis direction), the transmission axis of the polarizing section 81 is set at 0° with the Y-axis direction as the reference line. 12 and 13 and later-described FIGS. 15 and 16, the position of the polarizing portion is shown as a position on the XY plane, and the position of the laminated glass for vehicles is shown as a position on the XZ plane. At -200 mm and -400 mm points, which are areas diagonally forward of the viewer, the transmission axis of the polarizing unit 81 was rotated counterclockwise. The rotation angles were +10° and +25°, respectively. The counterclockwise direction is defined as +, and the clockwise direction is defined as -. The above experiment was performed by fixing the position of the viewer 35, shifting the position of each of the 150 mm x 150 mm square projection units in the X-axis direction by -200 mm each, and further shifting the image unit in the X-axis direction by -200 mm each, and similarly shifting the polarization unit in the X-axis direction by -200 mm each so that it was positioned between the projection unit and the image unit. In Comparative Example 1, as shown in FIG. 13, the transmission axis of the polarizing section 81 was set at 0° with the Y-axis direction as the reference line at all observation points.

[0100] FIG. 14 is a photograph showing the virtual images visually recognized in Example 1 and Comparative Example 1. When comparing positions at the same distance from the viewer, it was confirmed that in Example 1, the occurrence of double images was suppressed at points of -200 mm and -400 mm, which are in the diagonally forward area of ​​the viewer. On the other hand, in Comparative Example 1, double images extending in the horizontal and vertical directions were observed at these points.

[0101] Next, we present experimental results using the second HUD device. The experimental system itself is similar to that of the first HUD device shown in Fig. 11. A polarizing plate is used as the polarizing unit 82 used in the second HUD device instead of the polarizing unit 81. In addition, the viewer 35 observes a virtual image on an extension of the optical path based on the reflected image on the fourth principal surface 124. FIG. 15 is a diagram showing a schematic diagram of an experimental system in Example 2, and FIG. 16 is a diagram showing a schematic diagram of an experimental system in Comparative Example 2.

[0102] As shown in Figs. 15 and 16, the observation point was set to be a point in front of the viewer 35, which was set as position 0 in the X-axis direction, and points of -200 mm and -400 mm were set to the left of it. The left side of the X-axis is the "-" direction, and the right side is the "+" direction. In the second embodiment, as shown in FIG. 15, in the region in front of the viewer (position 0 in the X-axis direction), the transmission axis of the polarizing section 82 is set at 0° with the X-axis direction as the reference line. At -200 mm and -400 mm points, which are areas diagonally forward of the viewer, the transmission axis of the polarizing unit 82 was rotated clockwise. The rotation angles were -15° and -20°, respectively. The counterclockwise direction of the rotation angle is defined as +, and the clockwise direction is defined as -. The above experiment was performed by fixing the position of the viewer 35, shifting the position of each of the 150 mm x 150 mm square projection units in the X-axis direction by -200 mm each, and further shifting the image unit in the X-axis direction by -200 mm each, and similarly shifting the polarization unit in the X-axis direction by -200 mm each so that it was positioned between the projection unit and the image unit. In Comparative Example 2, as shown in FIG. 16, the transmission axis of the polarizing unit 82 was set at 0° with the X-axis direction as the reference line at all observation points.

[0103] FIG. 17 is a photograph showing the virtual images visually recognized in Example 2 and Comparative Example 2. When comparing positions at the same distance from the viewer, it was confirmed that in Example 2, the occurrence of double images was suppressed at points of -200 mm and -400 mm, which are in the diagonally forward area of ​​the viewer. On the other hand, in Comparative Example 2, double images extending in the horizontal and vertical directions were observed at these points.

[0104] Second embodiment A head-up display device (HUD device), a retardation film, a laminated glass for a vehicle, and a head-up display system (HUD system) according to a second embodiment of the present disclosure will be described with reference to the drawings.

[0105] Note that the HUD device according to the second embodiment of the present disclosure includes a HUD device having an imaging unit that irradiates projection light whose vibration direction is the X direction, and a HUD device having an imaging unit that irradiates projection light whose vibration direction is parallel to the YZ plane, and these are also referred to as a third HUD device and a fourth HUD device, respectively. In the description of the head-up display device according to the second embodiment of the present disclosure, when there is no need to distinguish between the third HUD device and the fourth HUD device, they are simply referred to as the HUD device according to the second embodiment of the present disclosure. In addition, the HUD system according to the second embodiment of the present disclosure is a system that can be used as a third HUD device or a fourth HUD device by switching the type of projection light emitted in one system.

[0106] The retardation film according to the second embodiment of the present disclosure is a retardation film usable for the laminated glass for vehicles, the HUD device, and the HUD system according to the second embodiment of the present disclosure. The laminated glass for vehicles according to the second embodiment of the present disclosure is a laminated glass for vehicles usable for the HUD device and the HUD system according to the second embodiment of the present disclosure.

[0107] First, a retardation film according to a second embodiment of the present disclosure will be described, and then a laminated glass for vehicles according to the second embodiment of the present disclosure will be described. Next, a HUD device according to a second embodiment of the present disclosure will be described, and finally, a HUD system according to the second embodiment of the present disclosure will be described.

[0108] [Retardation film] The retardation film according to the second embodiment of the present disclosure is a one-piece retardation film having a vertical axis in the up-down direction and a horizontal axis in the left-right direction, characterized in that the angle between the optical axis of the retardation film and the horizontal axis is constant at multiple points along the vertical axis, and the angle between the optical axis of the retardation film and the horizontal axis changes with a constant tendency along the horizontal axis. In the second embodiment of the present disclosure, the optical axis of the retardation film means the axis in the direction in which the refractive index of the retardation film is the largest. Moreover, the retardation film in the second embodiment of the present disclosure is a 1 / 2 wavelength film (half wavelength film).

[0109] FIG. 18 is a diagram illustrating an example of a retardation film according to the second embodiment of the present disclosure. 18 shows a schematic diagram of the optical axis of the retardation film at each point of the retardation film 201. Also, the directions of the "horizontal axis" and "vertical axis" are shown. At point P1 in FIG. 18, the angle between the optical axis of the retardation film and the horizontal axis is 45°. The angle between the optical axis of the retardation film and the horizontal axis is defined as the smaller angle between the two intersecting lines. When the optical axis and the horizontal axis of the retardation film are parallel, the angle between the optical axis and the horizontal axis of the retardation film is 0°. At points P1, P2, and P3 along the vertical axis, the angle between the optical axis of the retardation film and the horizontal axis is constant and is 45°.

[0110] In the retardation film according to the second embodiment of the present disclosure, the angle between the optical axis of the retardation film and the horizontal axis changes at a constant rate along the horizontal axis direction. FIG. 18 shows a retardation film in which the angle between the optical axis of the retardation film and the horizontal axis changes continuously along the horizontal axis direction.

[0111] The retardation film 201 shown in FIG. 18 shows points N1 and O1, which are located to the left of point P1 along the horizontal axis, and points Q1 and R1, which are located to the right of point P1 along the horizontal axis. At each point from left to right in Figure 18, the angle between the optical axis of the retardation film and the horizontal axis is 35° at point N1, 40° at point O1, 45° at point P1, 50° at point Q1, and 55° at point R1. It can be seen that the angle between the optical axis of the retardation film and the horizontal axis changes at a constant rate along the horizontal axis. In addition, since the angle between the optical axis and the horizontal axis of the retardation film changes continuously, for example, between points O1 and P1, the angle between the optical axis and the horizontal axis of the retardation film changes continuously from 40° to 45° at each point from left to right in FIG. 18.

[0112] FIG. 19 is a diagram illustrating an example of another retardation film according to the second embodiment of the present disclosure. FIG. 19 shows a retardation film in which the angle between the optical axis of the retardation film and the horizontal axis changes discontinuously along the horizontal axis direction. 19, a p1 region is shown near the center in the horizontal axis direction, where the angle between the optical axis of the retardation film and the horizontal axis is 45°. The width of the p1 region is shown by a double-headed arrow on the retardation film 202. In the p1 region, the angles between the optical axis and the horizontal axis of the retardation film are all the same, 45°.

[0113] The retardation film 202 shown in FIG. 19 shows an n1 region, which is a region located to the left of the p1 region along the horizontal axis, an o1 region, and a q1 region and an r1 region, which are regions located to the right of the p1 region along the horizontal axis. The boundaries of each region are indicated by dotted lines in FIG. The angle between the optical axis of the retardation film and the horizontal axis in each region is the same.

[0114] In each region from left to right in Figure 19, the angle between the optical axis of the retardation film and the horizontal axis is 35° in the n1 region, 40° in the o1 region, 45° in the p1 region, 50° in the q1 region, and 55° in the r1 region. It can be seen that the angle between the optical axis of the retardation film and the horizontal axis changes at a constant rate along the horizontal axis direction. Moreover, since the angle between the optical axis and the horizontal axis of the retardation film is the same in each region, it is understood that the angle between the optical axis and the horizontal axis of the retardation film changes discontinuously.

[0115] In the above description, a retardation film having a point or region where the angle between the optical axis and the horizontal axis of the retardation film is 45° has been described, but the specific value of the angle between the optical axis and the horizontal axis of the retardation film is not limited to the range of the above-mentioned example. A retardation film in which the angle between the optical axis and the horizontal axis of the retardation film changes with a constant tendency along the horizontal axis direction is a retardation film according to the second embodiment of the present disclosure. In addition, when the angle between the optical axis and the horizontal axis of the retardation film changes discontinuously, the width by which the angle changes between adjacent regions is not limited to 5°. In addition, the width by which the angle changes between adjacent regions does not have to be constant.

[0116] As the retardation film, a retardation element obtained by uniaxially or biaxially stretching a plastic film such as polycarbonate, polyarylate, polyethersulfone, cycloolefin polymer, triacetyl cellulose, polyethylene terephthalate (PET), or polyethylene naphthalate (PEN), or a retardation element obtained by orienting a liquid crystal polymer in a specific direction and fixing the orientation state can be used. The former retardation element obtained by uniaxially or biaxially stretching a plastic film can be produced by, for example, a solvent casting method in which a polymer resin is dissolved in a solvent, applied to a smooth surface such as a stainless steel belt or polyethylene terephthalate (PET), and the film is wound up after the solvent is evaporated, or a melt extrusion method in which a polymer resin is put into an extruder, heated and melted, extruded through a slit (T-die), cooled, and then wound up. A stretching machine is generally used for stretching, and retardation films stretched vertically, horizontally, obliquely, etc. can be obtained. As the latter retardation element, for example, a liquid crystal polymer can be applied onto a transparent substrate such as a transparent plastic film of oriented polyethylene terephthalate (PET) or triacetyl cellulose (TAC), and then heat-treated and cooled to fix the liquid crystal orientation. Examples of the liquid crystal polymer are not particularly limited as long as they are compounds that exhibit liquid crystallinity such as nematic liquid crystal, twisted nematic liquid crystal, discotic liquid crystal, and cholesteric liquid crystal when oriented in a specific direction. For example, those that exhibit twisted nematic orientation in the liquid crystal state and become glassy below the liquid crystal transition point can be used, and examples thereof include main-chain liquid crystal polymers such as optically active polyesters, polyamides, polycarbonates, and polyesterimides, and side-chain liquid crystal polymers such as optically active polyacrylates, polymethacrylates, polymerotes, and polysiloxanes. In addition, examples of polymer compositions that include these main-chain or side-chain polymers that are not optically active and other low-molecular or high-molecular optically active compounds are added.

[0117] Examples of the alignment treatment method include a method of rubbing the surface of a plastic film that will be a transparent substrate, a method of forming an organic thin film (alignment film) such as polyimide on a glass plate or plastic film, and rubbing or photoaligning the alignment film, etc. As the rubbing treatment, a method of rubbing the surface of the plastic film or alignment film with a rubbing cloth such as nylon or rayon can be used. The liquid crystal polymer can be applied by a commonly known method such as spin coating, die coating, spray coating, calendar coating, or gravure coating. In addition, a retardation film in which the angle between the optical axis and the horizontal axis of the retardation film changes discontinuously may be produced by laminating or bonding a plurality of retardation films with the optical axes of the retardation films tilted differently in each region.

[0118] A retardation film 201 shown in FIG. 18 and a retardation film 202 shown in FIG. 19 can both be used to obtain a laminated glass for a vehicle according to the second embodiment of the present disclosure, a HUD device according to the second embodiment of the present disclosure, and a HUD system according to the second embodiment of the present disclosure. That is, by using the retardation film according to the second embodiment of the present disclosure, it is possible to provide a HUD device having a wide display area in the lateral direction of the windshield surface.

[0119] [Laminated glass for vehicles] The laminated glass for vehicles according to the second embodiment of the present disclosure is a laminated glass for vehicles including a first glass plate, a second glass plate, and a retardation film disposed between the first glass plate and the second glass plate, characterized in that the retardation film is the retardation film according to the second embodiment of the present disclosure.

[0120] FIG. 20 is an exploded perspective view illustrating an example of a laminated glass for a vehicle according to the second embodiment of the present disclosure. The first glass plate has a first main surface exposed to the outside, and a second main surface opposite the first main surface. The second glass plate also has a fourth main surface exposed to the interior side, and a third main surface opposite the fourth main surface. FIG. 20 shows a laminated glass 210 for a vehicle. 20 shows a diagram in which the second glass plate 12 is disposed on the front side of the drawing, and the surface visible on the front side is the fourth main surface 124. The surface opposite to the fourth main surface 124 is the third main surface 123. The first glass plate 11 is disposed at the rear side of the drawing, and the surface seen at the front side is the second main surface 112. The surface opposite the second main surface 112 is the first main surface 111. Between the first glass plate 11 and the second glass plate 12, the retardation film 201 described with reference to FIG. The fourth main surface 124 is the surface exposed to the interior of the vehicle, and is therefore the surface that is directly viewed by a viewer when the laminated glass for vehicles is installed in a vehicle. That is, Fig. 20 shows the positional relationship in which a viewer directly views the glass from inside the vehicle.

[0121] This laminated glass for vehicles 210 is a laminated glass for vehicles for right-hand drive vehicles, and the viewer who views the HUD image is the driver. The position of the retardation film 201 is determined so that the point at which the angle between the optical axis and the horizontal axis of the retardation film becomes 45° is in front of the viewer who is the driver in a right-hand drive vehicle. In addition, the angle between the optical axis and the horizontal axis on the viewer's left side is smaller than 45°, and the angle between the optical axis and the horizontal axis on the viewer's right side is larger than 45°.

[0122] 20 shows a case where the optical axis slopes upward to the right in front of the viewer and the angle between the optical axis and the horizontal axis is 45°, but the optical axis may slope upward to the left in front of the viewer and the angle between the optical axis and the horizontal axis may also be 45°. When the optical axis slopes upward to the left in front of the viewer, the angle between the optical axis and the horizontal axis will be larger than 45° on the left side of the viewer, and the angle between the optical axis and the horizontal axis will be smaller than 45° on the right side of the viewer. In addition, when the optical axis slopes upward to the left, the angle between the optical axis and the horizontal axis will be an obtuse angle if taken in the same way as when the optical axis slopes upward to the right, so this refers to the value of the acute angle that is the supplementary angle of the obtuse angle.

[0123] In the laminated glass for vehicles, the first glass plate and the second glass plate are preferably bonded together via an interlayer film to form an integral structure. The interlayer film is heated at a temperature at which the polymer constituting the interlayer film softens to laminate the first glass plate and the second glass plate together. Examples of the polymer that can be used include polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), acrylic resin (PMMA), urethane resin, polyethylene terephthalate (PET), and cycloolefin polymer (COP). The interlayer film may be composed of multiple resin layers.

[0124] The retardation film is disposed between the first glass plate and the second glass plate. The retardation film may be disposed inside the interlayer film, or may be disposed in a position in contact with the first glass plate, or may be disposed in a position in contact with the second glass plate. By arranging the first glass plate and the second glass plate so that their lateral directions are aligned with the lateral axis direction of the retardation film, a laminated glass for a vehicle can be obtained as a windshield.

[0125] As the glass material constituting the laminated glass for vehicles, a flat glass plate processed into a curved shape can be suitably used. As the material of the glass plate, a material having a known glass composition such as soda-lime silicate glass as specified in ISO16293-1, aluminosilicate glass, borosilicate glass, non-alkali glass, etc. can be used. The thickness of each of the first glass plate and the second glass plate may be, for example, 0.4 mm to 3 mm. The distance between the first glass plate and the second glass plate may be 0.05 mm to 1 mm.

[0126] FIG. 20 shows a laminated glass for vehicles in which the retardation film 201 described in FIG. 18 is disposed. However, a laminated glass for vehicles in which the retardation film 202 described in FIG. 19 is used as the retardation film is also the laminated glass for vehicles according to the second embodiment of the present disclosure.

[0127] The laminated glass for vehicles according to the second embodiment of the present disclosure can be used to obtain a HUD device according to the second embodiment of the present disclosure and a HUD system according to the second embodiment of the present disclosure. That is, by using the laminated glass for vehicles according to the second embodiment of the present disclosure, a HUD device having a wide display area in the lateral direction of the windshield surface can be provided.

[0128] In addition, the area in which the HUD image is displayed may be expanded by using the above-mentioned laminated glass for a vehicle on the side windows in the same way as the windshield. In this case, it is preferable that the projection part where the projection light is projected is located in front of the viewer rather than directly to the side.

[0129] [Head-up display device (HUD device)] There are two types of HUD devices, a third HUD device and a fourth HUD device, in the second embodiment of the present disclosure. First, the definitions of the X-axis, Y-axis, and Z-axis, the definition of the moving body, and examples of the moving body, which are common to both HUD devices, are similar to the HUD device and the moving body in the first embodiment of the present disclosure.

[0130] As the laminated glass for a vehicle used in the HUD device, the laminated glass for a vehicle according to the second embodiment of the present disclosure can be used.

[0131] [Third HUD device] The third HUD device is a device in which a reflected image formed on the fourth main surface of the second glass plate is observed as a virtual image, and is an S-HUD type HUD device. FIG. 21 is a schematic diagram showing an overview of a third HUD device according to a first aspect of the second embodiment of the present disclosure and the optical paths in the device. In this schematic diagram, the viewer is a driver, and a schematic diagram of a cross section in a viewer's front area in front of the viewer is shown, and the direction perpendicular to the paper surface is the X-axis. In FIG. 21, the optical path of the projection light is shown by a solid line. In the third HUD device 3, the projection unit is a laminated glass 210 for a vehicle, and the laminated glass 210 for a vehicle includes a first glass plate 11 arranged on the exterior side of the vehicle, which is a moving body, and a second glass plate 12 arranged on the interior side of the vehicle. The first glass plate 11 has a first main surface 111 exposed to the outside, and a second main surface 112 opposite to the first main surface 111. The second glass plate 12 also has a fourth main surface 124 exposed to the interior side, and a third main surface 123 opposite to the fourth main surface 124. A retardation film 201 is disposed between the first glass plate 11 and the second glass plate 12 .

[0132] Projection light 240 is irradiated from image unit 31 to fourth principal surface 124, and a reflected image is formed on fourth principal surface 124. Viewer 35 observes a virtual image 412 on an extension of optical path 241 based on the reflected image formed on fourth principal surface 124.

[0133] In the third HUD device 3, the image unit 31 emits projection light 240 whose vibration direction is the X-axis direction. Here, a plane including three points, namely, light emitting point 32 of image section 31, reflection point 33 at which projection light 240 is reflected by fourth main surface 124, and viewpoint 34 of viewer 35, is the plane of incidence. In FIG. 21, the paper surface corresponds to approximately the same surface as the incident surface. Light whose vibration direction is perpendicular to the plane of incidence is S-polarized light. When the plane of incidence is perpendicular to the X-axis, if projection light whose vibration direction is in the X-axis direction is incident on the plane of incidence, the projection light will be S-polarized.

[0134] When the projection light is S-polarized light, it passes through the fourth principal surface 124 and travels through the projection section, where it is converted to P-polarized light by passing through the phase difference film 201. The projection light is then emitted to the outside as P-polarized light without being reflected at the first principal surface 111. If reflection at first main surface 111 can be suppressed in this manner, the occurrence of double images can be suppressed.

[0135] When a viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis that is at 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. If the optical axis of the retardation film 201, through which S-polarized light having a vibration direction along the X-axis transmits, is at 45°±5° with respect to the X-axis, a large proportion of S-polarized light will be converted to P-polarized light. In the area directly in front of the viewer, the incident surface is perpendicular to the X-axis and the projected light becomes S-polarized light, so the occurrence of double images can be suppressed by setting the optical axis of the corresponding retardation film at 45°±5° with respect to the X-axis.

[0136] Next, a case will be described where the viewer views a reflected image formed in a region diagonally forward of the viewer, which is a region that is farther away from the viewer's front region along any direction in the X-axis direction. When the viewer looks at an area diagonally ahead of the viewer, the plane of incidence is different from when the viewer looks at an area directly in front of the viewer. Since the vibration direction of the projected light remains in the X-axis direction, the vibration direction of the projected light (X-axis) relative to the plane of incidence shifts from the vertical direction, and the projected light becomes a mixture of S-polarized and P-polarized light, with the proportion of P-polarized components increasing the farther away from the area directly in front of the viewer. For such mixed light, if the optical axis of the retardation film is left at 45°±5° with respect to the X-axis, the proportion of P-polarized light in the projected light after passing through the retardation film will be small, and the proportion of S-polarized light will be high. Therefore, when a viewer views a reflected image formed in an area diagonally in front of the viewer, the optical axis of the retardation film placed in the area diagonally in front of the viewer is shifted from 45°±5° with respect to the X-axis, thereby increasing the proportion of the component that becomes P-polarized after the mixed light of S-polarized and P-polarized light passes through the retardation film, and suppressing the occurrence of double images.

[0137] In both the area directly in front of the viewer and the area diagonally in front of the viewer, the projection light is made incident on a retardation film so that the vibration direction of the projection light is converted to a direction parallel to the plane of incidence. Light whose vibration direction is parallel to the plane of incidence is P-polarized light. If the projected light after passing through the retardation film is P-polarized, no reflection occurs on the first principal surface, and the projected light is emitted to the outside of the vehicle as P-polarized light. This results in a HUD device that can suppress the occurrence of double images both in the area directly in front of the viewer and in the area diagonally forward of the viewer, and can suppress the occurrence of double images even when the HUD display area is expanded horizontally on the windshield surface.

[0138] FIG. 22 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area when the viewer is a driver of a right-hand drive vehicle. FIG. 22 shows only a laminated glass for vehicles 210 constituting the HUD device, and also shows the direction of the optical axis of a retardation film constituting the laminated glass for vehicles 210 in a schematic manner. In a right-hand drive vehicle, the right side of the vehicle laminated glass 210 in the drawing corresponds to the front of the viewer 35, so this portion is provided with a viewer front area 250. In the viewer front area 250, the optical axis of the retardation film is at 45°±5° with respect to the X-axis. The region that is farther from the viewer's frontal region 250 along the right direction in the X-axis direction is the right peripheral region 251. On the other hand, the region that is farther from the viewer's frontal region 250 along the left direction in the X-axis direction is the left peripheral region 252. In the right peripheral region 251, the optical axis of the retardation film is offset from the X-axis by more than 50°, while in the left peripheral region 252, the optical axis of the retardation film is offset from the X-axis by less than 40°. That is, in the right peripheral region and the left peripheral region, the direction in which the optical axis of the retardation film deviates from 45°±5° with respect to the X-axis is opposite. The same applies when the visual observer is a passenger in the passenger seat of a left-hand drive vehicle.

[0139] FIG. 23 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area in a left-hand drive vehicle. In a left-hand drive vehicle, the left side of the vehicle laminated glass 210 in the figure corresponds to the front of the viewer 35, so a viewer front region 250 is provided in this portion. In the viewer front region 250, the optical axis of the retardation film is at 45°±5° with respect to the X-axis. As in the embodiment shown in Fig. 22 , the region that is farther from the viewer front region 250 along the right direction in the X-axis direction is the right peripheral region 251, and the region that is farther from the viewer front region 250 along the left direction in the X-axis direction is the left peripheral region 252. In the right peripheral region 251, the optical axis of the retardation film is offset from the X-axis by more than 50°, while in the left peripheral region 252, the optical axis of the retardation film is offset from the X-axis by less than 40°. That is, in the right peripheral region and the left peripheral region, the direction in which the optical axis of the retardation film deviates from 45°±5° with respect to the X-axis is opposite. The same applies when the visual observer is a passenger in the passenger seat of a right-hand drive vehicle.

[0140] FIG. 24 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when the driver of a right-hand drive vehicle is the viewer. The direction of the optical axis of the retardation film is different from that shown in Fig. 22. In the embodiment shown in Fig. 22, the optical axis rises to the right in front of the viewer and the angle between the optical axis and the horizontal axis is 45°, whereas in the embodiment shown in Fig. 24, the optical axis rises to the left in front of the viewer and the angle between the optical axis and the horizontal axis is 45°. In the right peripheral region 251, the optical axis of the retardation film is offset from the X-axis by less than 40°, while in the left peripheral region 252, the optical axis of the retardation film is offset from the X-axis by more than 50°. That is, in the right peripheral region and the left peripheral region, the direction in which the optical axis of the retardation film deviates from 45°±5° with respect to the X-axis is opposite. The same applies when the visual observer is a passenger in the passenger seat of a left-hand drive vehicle.

[0141] FIG. 25 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when the driver of a left-hand drive vehicle is the viewer. The direction of the optical axis of the retardation film is different from that shown in Fig. 23. In the embodiment shown in Fig. 23, the optical axis rises to the right in front of the viewer and the angle between the optical axis and the horizontal axis is 45°, whereas in the embodiment shown in Fig. 25, the optical axis rises to the left in front of the viewer and the angle between the optical axis and the horizontal axis is 45°. In the right peripheral region 251, the optical axis of the retardation film is offset from the X-axis by less than 40°, while in the left peripheral region 252, the optical axis of the retardation film is offset from the X-axis by more than 50°. That is, in the right peripheral region and the left peripheral region, the direction in which the optical axis of the retardation film deviates from 45°±5° with respect to the X-axis is opposite. The same applies when the visual observer is a passenger in the passenger seat of a right-hand drive vehicle.

[0142] FIG. 26 is a diagram showing the positions of the viewer's front area and the viewer's diagonally forward area when there are two viewers, a driver and a passenger in the front passenger seat. In this embodiment, the driver and the passenger in the front passenger seat each see a different image. For each viewer, the angle between the optical axis of the retardation film and the X-axis is optimized in the viewer's front area and the viewer's diagonally forward area. When there are two viewers, a driver and a passenger in the front seat, a viewer front area 250 is provided for the viewer 35 as the driver shown on the right side of Figure 26, and a right peripheral area 251 is provided in an area that is farther away from the viewer front area 250 along the right direction of the X-axis. In addition, a viewer front area 250' is provided for a viewer 35' as a passenger in the passenger seat shown on the left side of Figure 26, and a left peripheral area 252' is provided in an area away from the viewer front area 250' along the left direction of the X-axis. Note that Figure 26 assumes a right-hand drive vehicle with the driver's seat on the right and the passenger seat on the left, but it is the same for a left-hand drive vehicle with the driver's seat on the left and the passenger seat on the right.

[0143] In the embodiment shown in FIG. 26, there is no left peripheral area for the viewer 35 as the driver and no right peripheral area for the viewer 35' as the passenger in the front passenger seat; however, these areas may be provided depending on the arrangement of the projection unit for the viewer 35 as the driver and the projection unit for the viewer 35' as the passenger in the front passenger seat. Moreover, a plurality of retardation films as shown in FIG. 20 may be combined so that the projected light can be viewed by each viewer.

[0144] FIG. 27 is a diagram showing another aspect of the positions of the viewer's front area and the viewer's diagonally forward area when there are two viewers, a driver and a passenger in the front passenger seat. The direction of the optical axis of the retardation film is different from that shown in Fig. 26. In the embodiment shown in Fig. 26, the optical axis rises to the right in front of the viewer and the angle between the optical axis and the horizontal axis is 45°, whereas in the embodiment shown in Fig. 27, the optical axis rises to the left in front of the viewer and the angle between the optical axis and the horizontal axis is 45°. In the right peripheral region 251 for the viewer 35 as a driver, the optical axis of the retardation film is shifted in a direction smaller than 40° with respect to the X-axis. On the other hand, in the left peripheral region 252' for the viewer 35' as a passenger in the passenger seat, the optical axis of the retardation film is shifted in a direction larger than 50° with respect to the X-axis.

[0145] The area diagonally forward of the viewer may be extended to an area diagonally forward of the viewer on a side glass disposed beside the viewer, or the projection portion may be extended onto the side glass. FIG. 28 is a diagram showing a schematic view of an aspect in which the projection unit is extended to the side window. 28 shows a side glass 270 disposed on the right side of the vehicle laminated glass 210. A viewer can visually recognize the projection light projected onto the right side glass 270. The area on the side glass 270 onto which the projection light is projected is referred to as a right-side extended area 271 . In the right-side extended region 271 as well, the angle of the optical axis of the retardation film changes in the peripheral region on the right side of the viewer's front area. The occurrence of double images can also be suppressed by using a similar concept in an extended area in which the area diagonally ahead of the viewer is extended to the side window.

[0146] [Fourth HUD Device] The fourth HUD device is a device in which a reflected image formed on the first main surface of the first glass plate is observed as a virtual image, and is a P-HUD type HUD device. FIG. 29 is a schematic diagram illustrating an overview of a fourth HUD device according to a second aspect of the second embodiment of the present disclosure and the optical paths in the device. In this schematic diagram, the viewer is a driver, and a schematic diagram of a cross section in a viewer's front area, which is in front of the viewer, is shown. The paper surface is a plane parallel to the YZ plane. In FIG. 29, the optical path of the projection light is shown by a solid line. In the fourth HUD device 4, the projection unit is a laminated glass 210 for a vehicle, and the laminated glass 210 for a vehicle includes a first glass plate 11 arranged on the exterior side of the vehicle, which is a moving body, and a second glass plate 12 arranged on the interior side of the vehicle. The first glass plate 11 has a first main surface 111 exposed to the outside, and a second main surface 112 opposite to the first main surface 111. The second glass plate 12 also has a fourth main surface 124 exposed to the interior side, and a third main surface 123 opposite to the fourth main surface 124. A retardation film 201 is disposed between the first glass plate 11 and the second glass plate 12 .

[0147] In the fourth HUD device 4, the image unit 31 emits projection light 260 whose vibration direction is parallel to the YZ plane. Here, a plane including three points, namely, light emitting point 32 of image section 31, reflection point 33 where projection light 260 is reflected by first main surface 111, and viewpoint 34 of viewer 35, is the plane of incidence. In FIG. 29, the paper surface corresponds to approximately the same surface as the incident surface. Light whose vibration direction is parallel to the plane of incidence is P-polarized light. When the plane of incidence is parallel to the YZ plane, if projection light whose vibration direction is parallel to the YZ plane is incident on the plane of incidence, the projection light will be P-polarized.

[0148] When the projected light 260 is P-polarized, it can also be used in sunglasses mode, where the virtual image is viewed through polarized sunglasses. Projection light 260 is irradiated from the image unit 31 to the fourth principal surface 124, and the projection light that travels inside the projection unit is converted into S-polarized light by the retardation film 201 and forms a reflected image on the first principal surface 111, while a portion of the S-polarized light that is not reflected passes through the first principal surface 111 and is emitted to the outside as S-polarized light. The reflected image formed on the first principal surface 111 passes through the retardation film 201 again and is converted into P-polarized light. The viewer 35 visually recognizes a virtual image 612 on the extension of the optical path 261 based on the reflected image on the first principal surface 111. Since the virtual image 612 is made of P-polarized light, the viewer 35 can view the virtual image even through the polarized sunglasses 36.

[0149] Incidentally, either no reflected image or a small reflected image is formed on the fourth principal surface 124. When the intensity of the reflected image formed on the fourth principal surface 124 is relatively strong compared to the reflected image on the first principal surface 111, the reflected image formed on the fourth principal surface 124 is observed as a double image.

[0150] When a viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis that is at 45°±5° with respect to the X-axis in a plane parallel to the fourth principal surface. In the area directly in front of the viewer, most of the projected light becomes P-polarized light. If the optical axis of the retardation film 201 that transmits P-polarized light in the area directly in front of the viewer is at an angle of 45°±5° to the X-axis, then a large proportion of the P-polarized light will be converted to S-polarized light. If the efficiency of converting the projection light (P-polarized light) incident on the retardation film into S-polarized light is high, the virtual image based on the reflected image formed on the first main surface of the first glass plate will be stronger. Therefore, the influence of the reflected image formed on the fourth main surface will be relatively weaker, and the occurrence of double images will be suppressed.

[0151] Next, a case will be described where the viewer views a reflected image formed in a region diagonally forward of the viewer, which is a region that is farther away from the viewer's front region along any direction in the X-axis direction. When the viewer looks at an area diagonally ahead of the viewer, the plane of incidence is different from when the viewer looks at the area directly in front of the viewer. Since the vibration direction of the projected light remains parallel to the YZ plane, the vibration direction of the projected light with respect to the plane of incidence (parallel to the YZ plane) deviates from the parallel direction, and the projected light becomes a mixture of S-polarized and P-polarized light, with the proportion of S-polarized components increasing the farther it is from the area directly in front of the viewer. For such mixed light, if the optical axis of the retardation film is left at 45°±5° with respect to the X-axis, the proportion of S-polarized light in the projected light after passing through the retardation film will be small, and the proportion of P-polarized light will be high. Therefore, when a viewer views a reflected image formed in an area diagonally in front of the viewer, the optical axis of the retardation film arranged in the area diagonally in front of the viewer is shifted from 45°±5° with respect to the X-axis, thereby increasing the proportion of components that become S-polarized light after the mixed light of S polarized light and P polarized light passes through the retardation film, and strengthening the virtual image display based on the reflected image formed on the first main surface of the first glass plate. By strengthening the virtual image display based on the reflected image formed on the first principal surface, the influence of the projected light reflected by the fourth principal surface is relatively weakened, and the occurrence of double images is suppressed.

[0152] In both the area directly in front of the viewer and the area diagonally in front of the viewer, the vibration direction of the projection light is converted to a direction perpendicular to the plane of incidence by making the projection light enter a retardation film. Light whose vibration direction is perpendicular to the plane of incidence is S-polarized light. If the projection light after passing through the retardation film is S-polarized light, the reflection from the first principal surface is strong, and therefore the virtual image display based on the reflected image formed on the first principal surface of one glass plate is strong. Therefore, the occurrence of double images is suppressed both in the area directly in front of the viewer and in the area diagonally forward of the viewer, resulting in a HUD device that can suppress the occurrence of double images even when the HUD display area is expanded laterally across the windshield surface.

[0153] In the fourth HUD device, the positions of the viewer's front area and the viewer's diagonally forward area can be determined in the same manner as in the third HUD device. Examples of the positions of the viewer's front area and the viewer's diagonally forward area in a right-hand drive vehicle and a left-hand drive vehicle can be as described with reference to Figures 22 and 23. Moreover, an example in which the optical axis of the retardation film slopes upward to the left can be as described with reference to FIGS. Moreover, an example in which there are two viewers can be as described with reference to FIGS. 26 and 27. FIG. Moreover, an example in which the projection unit is extended to the side window can be as described with reference to FIG.

[0154] In the third and fourth HUD devices described so far, the change in the tilt of the direction of the optical axis of the retardation film in the region diagonally forward of the viewer is continuous along the X-axis direction (i.e., an example using the retardation film shown in FIG. 18 ). However, it is also possible to use a HUD device in which the change in the tilt of the direction of the optical axis of the retardation film in the region diagonally forward of the viewer is discontinuous along the X-axis direction (i.e., an example using the retardation film shown in FIG. 19 ).

[0155] [Head-up display system (HUD system)] The HUD system according to the second embodiment of the present disclosure is a system that can be used as a third HUD device or a fourth HUD device by switching the type of projection light emitted in one system. In the HUD system, the image unit can switch between emitting a first projection light whose vibration direction is in the X-axis direction and a second projection light whose vibration direction is parallel to the YZ plane. When emitting the first projection light, it becomes an S-HUD and can be used as a third HUD device. When emitting the second projection light, it becomes a P-HUD and can be used as a fourth HUD device. When the viewer views a virtual image through a polarizing plate such as polarized sunglasses, it is used as a fourth HUD device. The configuration of the HUD system other than the video unit can be the same as that of the third HUD device and the fourth HUD device. The switching between the first projection light and the second projection light in the imaging section will be described below.

[0156] The imaging unit may be a device capable of projecting a first projection light whose vibration direction is in the X-axis direction, or a device capable of projecting a second projection light whose vibration direction is parallel to the YZ plane. Alternatively, the device may have two types of projection mechanisms and be capable of switching between the types of projection light. The device may also be capable of converting the light to be projected into a first projection light or a second projection light by first irradiating light of a certain polarized light and then placing a polarization control unit in the optical path of the light. The types of projection light before conversion include light that randomly contains all kinds of polarization (unpolarized), circularly polarized light, elliptically polarized light, a mixture of P-polarized and S-polarized light, and linearly polarized light that is neither P-polarized nor S-polarized. A projector capable of emitting projection light is preferably used as the image unit. Examples of such a projector include a DMD projection system projector, a laser scanning MEMS projection system projector, and a reflective liquid crystal projector.

[0157] For example, if the imaging unit has a mechanism for initially irradiating a first projection light whose vibration direction is in the X-axis direction, the first projection light can be converted into a second projection light by providing a half-wave plate (a retardation film whose optical axis is at 45° with respect to the vibration direction of the first projection light) as a polarization control unit in the optical path of the projection light. When the first projection light is used as it is as the projection light, it is not allowed to pass through the polarization control section, and when it is used as the second projection light, it is allowed to pass through the polarization control section. By controlling the passage / non-passage of the polarization control section, it is possible to switch between the first projection light and the second projection light.

[0158] Even if the image unit has a mechanism for initially irradiating a second projection light whose vibration direction is parallel to the YZ plane, the second projection light can be converted into the first projection light by using a similar configuration, and therefore, by controlling the pass / non-pass of the polarization control unit, it is possible to switch between the second projection light and the first projection light.

[0159] In the fourth HUD device, the reflected image formed on the first main surface of the first glass plate is observed as a virtual image, but when the intensity of the projected light is the same as in the third HUD device, the virtual image displayed is weaker than the reflected image formed on the fourth main surface of the second glass plate in the third HUD device. Therefore, it is preferable to set the irradiation intensity when the second projection light is projected to be higher than the irradiation intensity when the first projection light is projected. This can be achieved by switching the irradiation intensity of the projection light emitted from the image unit between the first projection light and the second projection light. In addition, when the first projection light is projected, the irradiation intensity may be reduced by passing the light through an ND filter or the like.

[0160] (Example according to the second embodiment of the present disclosure) An experiment was conducted to compare the occurrence of double images when the angle between the optical axis of the retardation film and the X-axis was changed in both the front area and the diagonally forward area of ​​the viewer. First, experimental results for the case where the area diagonally ahead of the viewer is on the right side of the viewer will be shown. Fig. 30 is a schematic diagram of the layout of the third HUD device used in the examples and comparative examples. Fig. 31 is a schematic diagram of the experimental system in Example 3, and Fig. 32 is a schematic diagram of the experimental system in Comparative Example 3.

[0161] A third HUD device was prepared as shown in Fig. 30. The third HUD device 3 has a square projection area of ​​200 mm x 200 mm for the S-HUD system. As shown in FIG. 30, the image portion 31 is placed horizontally, and the laminated glass for vehicles 210 is disposed in a positional relationship of 56° to the image portion 31 so as to form a Brewster's angle. Projection light oscillating in the X-axis direction is emitted vertically upward from the image unit 31, and a viewer 35 observes a virtual image displayed on the fourth principal surface 124. The viewer's viewpoint is at the same height as the laminated glass for vehicles. A tablet is used as the image unit 31, and a white lattice image is displayed from the tablet. The tablet is placed directly under the laminated glass for the vehicle. In order to simulate nighttime driving of a moving object, a black background plate 37 is disposed on the other side of the laminated glass for vehicles 210 in the direction of the viewer 35's view.

[0162] As shown in Figs. 31 and 32, the observation point was set to be position 0 in the X-axis direction, directly in front of the viewer, and positions +200 mm and +400 mm were set to the right. In Example 3, as shown in Fig. 31, the projection unit was arranged so that the optical axis of the retardation film was at 45° with respect to the X axis in the region in front of the viewer (position 0 in the X-axis direction). Furthermore, the projection unit was arranged so that the optical axis of the retardation film was at 55° and 65° with respect to the X axis at positions +200 mm and +400 mm, which are regions diagonally in front of the viewer, respectively. The above experiment was carried out by shifting the position of the 200 mm x 200 mm square projection unit by 200 mm, and further by tilting the projection unit, positioning the projection unit so as to tilt the optical axis of the retardation film. In Comparative Example 3, as shown in FIG. 32, the projection unit was positioned so that the optical axis of the retardation film was at 45° with respect to the X-axis at all observation points.

[0163] FIG. 33 is a photograph showing the virtual images visually recognized in Example 3 and Comparative Example 3. When comparing positions at the same distance from the viewer, it was confirmed that in Example 3, the occurrence of double images was suppressed at points of +200 mm and +400 mm, which are in the diagonally forward area of ​​the viewer. On the other hand, in Comparative Example 3, double images extending laterally were observed at these points.

[0164] Next, experimental results for the case where the diagonally forward area of ​​the viewer is on the left side of the viewer will be shown. 34 is a diagram showing a schematic diagram of an experimental system in Example 4, and FIG. 35 is a diagram showing a schematic diagram of an experimental system in Comparative Example 4. The experimental method was the same as in Example 3. As shown in Figures 34 and 35, the observation points were set to the left of the viewer's position, -100 mm, -200 mm, -300 mm, -400 mm, and -500 mm, with the viewer's front being set as position 0 in the X-axis direction. As shown in FIG. 34, in Example 4, the optical axis of the retardation film in the region directly in front of the viewer (position 0 in the X-axis direction) was set to 45° with respect to the X-axis, and the optical axis of the retardation film in the regions diagonally in front of the viewer, at positions −100 mm, −200 mm, −300 mm, −400 mm, and −500 mm, was set to 40°, 35°, 30°, 25°, and 20°, respectively, with respect to the X-axis. As shown in FIG. 35, in Comparative Example 4, the optical axis of the retardation film was set at 45° with respect to the X-axis at all observation points.

[0165] FIG. 36 is a photograph showing the virtual images visually recognized in Example 4 and Comparative Example 4. When comparing positions at the same distance from the viewer, it was confirmed that in Example 4, the occurrence of double images was suppressed at -100 mm, -200 mm, -300 mm, -400 mm, and -500 mm, which are areas diagonally forward of the viewer. On the other hand, in Comparative Example 4, double images extending laterally were observed particularly at the -300 mm point, the -400 mm point, and the -500 mm point. [Industrial Applicability]

[0166] It is possible to provide a HUD device that can suppress the occurrence of double images when a viewer views an image displayed in an area near the outer periphery of the windshield surface of a vehicle such as an automobile, or in the central area of ​​the windshield surface from an oblique angle.

[0167] This application claims priority under the Paris Convention or the laws of a country transitioning thereto based on Japanese Patent Application No. 2020-022342 filed on February 13, 2020, Japanese Patent Application No. 2020-027920 filed on February 21, 2020, and Japanese Patent Application No. 2020-140713 filed on August 24, 2020. The contents of these applications are incorporated by reference in their entirety into this application. [Explanation of symbols]

[0168] 1. First HUD Device 2 Second HUD Device 3. Third HUD Device 4. The fourth HUD device 10, 210 Laminated glass for vehicles 11 First glass plate 12 Second glass pane 20 Vehicles 31 Video Section 32 Light Point 33 reflection point 34 Viewpoints 35 Viewer 35D Driver (visitor) 35P Passenger (visitor) 36 Polarized sunglasses 40, 60 projection light 41 Projected light after passing through the polarizing section 42, 241 Optical path based on the reflected image formed on the fourth principal surface 61 Projected light after passing through the polarizing section 62, 261 Optical path based on the reflected image formed on the first principal surface 81, 81L, 81R, 81D, 81P, 82, 82L, 82R, 82D, 82P Polarizing unit 100, 201, 202 Retardation film 111 First principal surface 112 Second principal surface 123 Third principal surface 124 Fourth principal plane 240 Projection light with vibration direction in the X-axis direction 250, 250' Viewer front area of ​​the second embodiment 251 Right peripheral area (area diagonally forward of the viewer in the second embodiment) 252, 252′: Left peripheral area (area diagonally forward of the viewer in the second embodiment) 260 Projection light whose vibration direction is parallel to the YZ plane 270 Side glass 271 Right side expansion area 412, 421, 421C, 421L, 421R Virtual images (virtual images on the extension of the optical path based on the reflected image formed on the fourth main surface) 612, 621, 621C, 621L, 621R Virtual image (virtual image on the extension of the optical path based on the reflected image formed on the first principal surface)

Claims

1. A head-up display device that is mounted on a moving body and allows a viewer, who is an occupant of the moving body, to recognize a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display device includes: an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit as a separate member from the image unit, the polarizing unit transmitting light that is included in the projection light and vibrates in a specific direction; a projection unit onto which the projection light transmitted through the polarizing unit is projected, the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away than the viewer front area along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer views the projection unit is 0°, and the plane along the retardation film is the projection plane, the retardation film has an optical axis inclined by θr with respect to the X-axis on the projection surface, and changes the vibration direction of the projection light incident on the projection surface by the optical axis; A head-up display device, wherein the specific direction is a direction parallel to the incident surface.

2. The head-up display device according to claim 1 , wherein the viewer observes a virtual image based on a reflected image formed on a surface other than an interior surface of the second glass plate.

3. The head-up display device according to claim 1 , wherein the viewer observes a virtual image based on a reflected image formed on the exterior side surface of the first glass plate.

4. A head-up display device that is mounted on a moving body and allows a viewer, who is an occupant of the moving body, to recognize a virtual image based on a reflected image of projection light at a projection unit, The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display device includes: an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit, for transmitting light that is included in the projection light and that vibrates in a specific direction; a projection unit onto which the projection light transmitted through the polarizing unit is projected, the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away than the viewer front area along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer views the projection unit is 0°, and the plane along the retardation film is the projection plane, the retardation film has an optical axis inclined by θr with respect to the X-axis on the projection surface, and rotates the vibration direction of the projection light incident on the projection surface by 2dθ when an angle between the vibration direction θα of the projection light incident on the projection surface and the optical axis is dθ; The head-up display device is characterized in that the vibration direction θα is a direction of 2θr-θp on the projection surface when the angle of the incident surface with respect to the X-axis on the projection surface is θp.

5. The head-up display device according to claim 4, wherein the viewer observes a virtual image based on a reflected image formed on the interior side of the second glass plate.

6. The viewer is a plurality of people, The polarizing unit is provided between the image unit and the projection unit for each viewer, and each entrance surface is provided for each viewer, 6. The head-up display device according to claim 1, wherein each of the polarizing sections transmits projection light that vibrates in the specific direction corresponding to each of the incidence surfaces.

7. the polarizing unit has a transmission axis such that the vibration direction of the transmitted projection light is the specific direction, The head-up display device according to claim 6 , wherein the directions of the transmission axes are different from each other.

8. 8. The head-up display device according to claim 7, wherein the projected light is projected onto a central region that is between the viewer front regions of each of the multiple viewers and corresponds to the viewer diagonally forward region of each of the multiple viewers.

9. a projection position at which the projection light is projected is changeable in the projection unit, A head-up display device as described in any one of claims 1 to 8, wherein the polarizing section is movable and the vibration direction of the light passing through the polarizing section can be changed in response to a change in the incident plane accompanying a change in the projection position.

10. A head-up display system that is mounted on a moving body and allows a viewer, who is a passenger of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display system includes: an imaging unit that irradiates the projection light; a polarizing unit provided between the image unit and the projection unit, for transmitting light that is included in the projection light and that vibrates in a specific direction; The projection unit projects the projection light, the projection unit is a laminated glass in which a second glass plate, a retardation film, and a first glass plate are arranged in this order from an indoor side, which is an incident side of the projection light, to an outdoor side, a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away than the viewer front area along any direction in the X-axis direction, The projection light is projected at least toward a region diagonally forward of the viewer, When the X-axis when the viewer views the projection unit is 0°, and the plane along the retardation film is the projection plane, the retardation film has an optical axis inclined by θr with respect to the X-axis on the projection surface, and changes the vibration direction of the projection light incident on the projection surface by the optical axis; A head-up display system, characterized in that the polarizing unit is movable and the vibration direction of light passing through the polarizing unit is changed, thereby making it possible to switch between the following (A) and (B). (A) The vibration direction of light incident on the second glass plate is parallel to the incident surface. (B) When the angle between the vibration direction θα of the projection light incident on the projection surface and the optical axis is dθ, the retardation film rotates the vibration direction of the incident projection light by 2dθ, and when the angle of the incident surface with respect to the X-axis on the projection surface is θp, the vibration direction of the light transmitted through the second glass plate is set to a direction of 2θr-θp on the projection surface.

11. a projection position at which the projection light is projected is changeable in the projection unit, The head-up display system according to claim 10 , wherein the polarizing section is movable in response to a change in the plane of incidence accompanying the change in the projection position, and the vibration direction of the projection light passing through the polarizing section can be changed.

12. A head-up display device that is mounted on a moving body and allows a viewer, who is a passenger of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, the head-up display device comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display device includes: an imaging unit that irradiates the projection light whose vibration direction is the X-axis direction; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, the second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction parallel to the incident surface, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film that is at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film arranged in the region obliquely forward of the viewer is inclined in a direction such that an optical axis of the retardation film is deviated from 45°±5° with respect to an X-axis in a plane parallel to the fourth main surface, The virtual image is based on a reflected image formed on the fourth main surface of the second glass plate, a head-up display device, characterized in that in both the viewer's front area and the viewer's diagonally forward area, the light emitted from the first main surface of the first glass plate is the projection light that mainly vibrates in a direction parallel to the incident surface.

13. A head-up display device that is mounted on a moving body and allows a viewer, who is a passenger of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, the head-up display device comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display device includes: An imaging unit that irradiates the projection light whose vibration direction is parallel to the YZ plane; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, the second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction perpendicular to the incident surface, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film that is at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film arranged in the region obliquely forward of the viewer is inclined in a direction such that an optical axis of the retardation film is deviated from 45°±5° with respect to an X-axis in a plane parallel to the fourth main surface, The virtual image is based on a reflected image formed on the first main surface of the first glass plate, a head-up display device characterized in that in both the viewer's front area and the viewer's diagonally forward area, the light reflected by the first main surface of the first glass plate is the projection light that mainly vibrates in a direction perpendicular to the incident surface.

14. 14. The head-up display device according to claim 12 or 13, wherein in the region diagonally forward of the viewer, a right peripheral region located to the right of the viewer's front area and a left peripheral region located to the left of the viewer's front area are opposite in the direction in which the optical axis of the retardation film is shifted from 45°±5° with respect to the X-axis.

15. The head-up display device according to any one of claims 12 to 14, wherein the change in the inclination of the direction of the optical axis of the retardation film in the region diagonally forward of the viewer is made continuous along the X-axis direction.

16. The head-up display device according to any one of claims 12 to 14, wherein the change in the inclination of the direction of the optical axis of the retardation film in the region diagonally forward of the viewer is discontinuous along the X-axis direction.

17. A laminated glass for vehicles comprising a first glass plate, a second glass plate, and a retardation film disposed between the first glass plate and the second glass plate, the retardation film is an integral retardation film having a vertical axis in the up-down direction and a horizontal axis in the left-right direction, wherein an angle between an optical axis of the retardation film and the horizontal axis is constant at a plurality of points along the vertical axis, and an angle between the optical axis of the retardation film and the horizontal axis changes with a constant tendency along the horizontal axis.

18. A laminated glass for vehicles as described in claim 17, wherein the angle between the optical axis of the retardation film and the horizontal axis changes continuously along the horizontal axis direction.

19. A laminated glass for vehicles as described in claim 17, wherein the angle between the optical axis of the retardation film and the horizontal axis changes discontinuously along the horizontal axis direction.

20. A head-up display system that is mounted on a moving body and allows a viewer, who is a passenger of the moving body, to view a virtual image based on a reflected image of projection light at a projection unit, comprising: The direction parallel to the ground and perpendicular to the moving direction when the moving body moves forward is defined as the X-axis, the direction parallel to the ground and the moving direction when the moving body moves forward is defined as the Y-axis, and the direction perpendicular to the ground is defined as the Z-axis. When a surface having the viewpoint of the viewer, the light emitting point of the projection light, and the reflection point where the projection light is reflected is defined as an incident surface, The head-up display system includes: an imaging unit that irradiates the projection light; a projection unit onto which the projection light is projected, the projection unit is disposed in a traveling direction relative to the viewer when the moving body moves forward, and is made of laminated glass including a second glass plate disposed on an incident side of the projection light, a first glass plate disposed on an exit side of the projection light, and a retardation film disposed between the second glass plate and the first glass plate; The first glass plate has a first main surface exposed to an exterior side and a second main surface opposite to the first main surface, the second glass plate has a fourth main surface exposed to the interior side and a third main surface opposite the fourth main surface, By making the projection light incident on the retardation film, the vibration direction of the projection light can be converted to a direction parallel to or perpendicular to the incident surface, the projection unit has a viewer front area that is in front of the viewer, and a viewer diagonally forward area that is an area that is farther away from the viewer front area along any direction in the X-axis direction, When the viewer views the reflected image formed in the viewer's front area, the retardation film arranged in the viewer's front area has an optical axis of the retardation film that is at an angle of 45°±5° with respect to the X-axis in a plane parallel to the fourth main surface, When the viewer views a reflected image formed in the region obliquely forward of the viewer, the retardation film arranged in the region obliquely forward of the viewer is inclined in a direction such that an optical axis of the retardation film is deviated from 45°±5° with respect to an X-axis in a plane parallel to the fourth main surface, the imaging unit can switch between irradiating a first projection light whose vibration direction is an X-axis direction and a second projection light whose vibration direction is a direction parallel to a YZ plane; When the viewer views a virtual image without using a polarizing plate, the first projection light is irradiated from the image unit, and the virtual image is based on a reflected image formed on the fourth main surface of the second glass plate, and in both the viewer's front area and the viewer's obliquely forward area, the light emitted from the first main surface of the first glass plate is projection light that mainly vibrates in a direction parallel to the incident surface, A head-up display system characterized in that, when the viewer views a virtual image through a polarizing plate, the second projection light is irradiated from the imaging unit, and the virtual image is based on a reflected image formed on the first main surface of the first glass plate, and in both the viewer's front area and the viewer's diagonally forward area, the light reflected on the first main surface of the first glass plate is projection light that mainly vibrates in a direction perpendicular to the incident surface.

Images