Display device for vehicle

Abstract

A vehicle display device is provided with: a display device that emits a display image projected onto a windshield disposed in front of a driver as display light via a display unit; and at least one reflecting mirror that reflects the display light on an optical path of the display light from the display device to the reflecting body. A liquid crystal panel, which switches the polarization direction by applying a voltage, is disposed on the optical path of the display light between the mirror and the display unit in a state of being sandwiched between the first polarizing plate and the second polarizing plate. A first polarizing plate that transmits one of the P-polarized light and the S-polarized light is disposed on the upper surface of the liquid crystal panel, and a second polarizing plate that transmits the other of the P-polarized light and the S-polarized light is disposed on the lower surface of the liquid crystal panel.

Description

Technical Field

[0001] This invention relates to a display device for vehicles. Background Technology

[0002] In automobiles and other vehicles, there are vehicles equipped with a vehicle display device also known as a head-up display (HUD) (see Japanese Patent Application Publication No. 2024-007661). The vehicle display device includes: a display (image display device) that generates and outputs display light; a reflector that reflects the display light emitted from the display towards a projection section (a reflector positioned in front of the vehicle occupants); and a housing that houses the display and the reflector. This vehicle display device is configured to project the displayed image onto the projection section (reflector) via the reflector or the like, thereby allowing the driver to perceive a virtual image. Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] However, in conventional vehicle display devices, when the display is turned off in a vehicle, external light, including sunlight, enters the interior of the display device and shines on the display unit, potentially causing the display unit to overheat and break. In the structure of the vehicle display device, the focal point of the reflector is located on the display unit, and the tendency for incident external light to concentrate on the display unit is also a major cause of the temperature rise. As a method to prevent external light from entering the display unit, as disclosed in Japanese Patent Application Publication No. 2024-007661, there are methods that drive a reflector to adjust the reflection angle of external light, but this requires providing space inside the vehicle display device for driving the reflector.

[0005] The present invention was made in view of the problems inherent in such prior art. Moreover, the object of the present invention is to provide a display device for a vehicle that can prevent external light from entering the display section without driving a reflector.

[0006] means for solving problems

[0007] The vehicle display device according to the present invention includes: a display device that emits a display image projected onto a reflector disposed in front of a vehicle occupant as display light via a display unit; and at least one reflector that reflects the display light along the optical path of the display light from the display device to the reflector. A liquid crystal panel, whose polarization direction can be switched by applying a voltage, is disposed between a first polarizing plate and a second polarizing plate in the optical path of the display light between the reflector and the display unit. A first polarizing plate, through which one of P-polarized light and S-polarized light passes, is disposed on the upper surface of the liquid crystal panel, and a second polarizing plate, through which the other of P-polarized light and S-polarized light passes, is disposed on the lower surface of the liquid crystal panel.

[0008] Invention Effects

[0009] According to the present invention, a vehicle display device can be provided that prevents external light from entering the display section without driving a reflector. Attached Figure Description

[0010] Figure 1 This is a schematic structural diagram showing an example of a vehicle equipped with the vehicle display device of this embodiment.

[0011] Figure 2 This is a schematic structural diagram showing an example of a vehicle display device according to this embodiment.

[0012] Figure 3 It is a three-dimensional view of the display device.

[0013] Figure 4 This is a side view of the display device.

[0014] Figure 5 This is a schematic diagram showing the state of the liquid crystal panel sandwiched between the first polarizing plate and the second polarizing plate.

[0015] Figure 6 It is shown Figure 4 The top enlarged view of the display device.

[0016] Figure 7 This is a schematic diagram showing the transmission of external light without applying voltage to the liquid crystal panel.

[0017] Figure 8 This is a schematic diagram showing the transmission of external light when a voltage is applied to the liquid crystal panel.

[0018] Figure 9 This is a schematic structural diagram showing an example of a vehicle display device according to this embodiment.

[0019] Figure 10 This is a schematic diagram showing the situation where external light is incident on the top of a conventional vehicle display device.

[0020] Figure 11 This is a schematic diagram showing the situation where external light is incident on the top of the display device.

[0021] Figure 12 This is a schematic diagram showing the situation where external light is incident on the top of the display device. Detailed Implementation

[0022] Hereinafter, the vehicle display device of this embodiment will be described in detail with reference to the accompanying drawings. Furthermore, the scale of the drawings has been exaggerated for ease of explanation and may sometimes differ from the actual scale.

[0023] like Figure 1 As shown, the vehicle display device 1 in this embodiment is, for example, a head-up display device mounted on a vehicle 100 such as an automobile. The vehicle display device 1 is disposed together with the instrument cluster 103 inside the instrument panel 101, and displays a virtual image V in front of the eye point EP of the vehicle 100. The eye point EP is a predetermined position as the viewpoint position of the vehicle occupant (driver D) sitting in the driver's seat.

[0024] A vehicle display device 1 is disposed inside the instrument panel 101 of the vehicle 100. An upper surface opening 101a is provided on the upper surface of the instrument panel 101, through which the vehicle display device 1 projects an image onto the windshield WS. The windshield WS is a reflector disposed in the vehicle 100 in front of the driver D. The windshield WS is, for example, semi-transparent, reflecting light incident from the vehicle display device 1 towards the eye point EP. The driver D perceives the image reflected by the windshield WS as a virtual image V. The virtual image V is perceived by the driver D as existing in front of the windshield WS.

[0025] like Figure 2 As shown, the vehicle display device 1 of this embodiment is configured to include reflectors 20 and 21, a display device 30, a control unit 40, and a frame 50.

[0026] The frame 50 is, for example, molded from synthetic resin material into a box shape, and has an internal space. The frame 50 houses and holds the reflectors 20 and 21, the display device 30, and the control unit 40 within the internal space. The frame 50 has an opening 60 that connects the exterior of the frame 50 to the internal space. This opening 60 is located on the upper wall of the frame 50, opposite the windshield WS. Additionally, a cover member 61 made of a light-transmitting synthetic resin material (e.g., acrylic resin) is provided on the upper wall of the frame 50 to close the opening 60. The vehicle display device 1 emits display light 11 from the frame 50 through the opening 60 toward the windshield WS. The display light 11 is light emitted from the display device 30 and reflected by the reflectors 20 and 21.

[0027] The control unit 40 is electrically connected to the display device 30 and controls the display of the image (virtual image V) displayed on the vehicle display device 1. This control unit 40 is, for example, composed of an IC chip and is driven by power obtained from the battery within the vehicle 100. Additionally, the control unit 40 can also be connected to the ECU (Electronic Control Unit) within the vehicle 100 to transmit and receive signals with the ECU.

[0028] The display device 30 emits a display image projected onto the windshield WS as display light 11. The display device 30 is configured to include a backlight housing 31, a display unit 32, a liquid crystal panel 33, a first polarizing plate 34, and a second polarizing plate 35.

[0029] A backlight unit (not shown) is provided inside the backlight housing 31. The backlight unit outputs display light 11 for displaying images, illuminating the display unit 32 from the rear side. The display unit 32 emits light from its surface display surface by being illuminated from the rear side. Furthermore, the display device 30 emits the display image projected onto the windshield WS as display light 11 via the display unit 32.

[0030] The vehicle display device 1 has at least one reflector 20, 21 in the optical path of the display light 11 from the display device 30 to the windshield WS. The reflectors 20, 21 reflect the display light 11 emitted from the display device 30 toward the windshield WS. Figure 2 As shown, at least one reflector 20, 21 may have a first reflector 20 and a second reflector 21.

[0031] The first reflector 20 is positioned opposite the opening 60 of the frame 50, and is located in the optical path between the opening 60 of the frame 50 and the second reflector 21. The reflective surface of the first reflector 20 can be formed by a concave or convex curved surface, or it can be a concave mirror. This first reflector 20 causes the display light 11 reflected by the second reflector 21 to be totally internally reflected towards the windshield WS through the opening 60. Alternatively, a reflective layer can be formed on the reflective surface of the first reflector 20 by means of vapor deposition or the like.

[0032] The first reflecting mirror 20 functions as a magnifying glass. That is, the first reflecting mirror 20 magnifies and reflects the display image in such a way that the display image represented by the display light 11 after being reflected by the first reflecting mirror 20 is relatively larger than the display image represented by the display light 11 before being reflected by the first reflecting mirror 20.

[0033] The second reflector 21 is positioned opposite the display device 30. The reflective surface of the second reflector 21 can be formed by a flat surface or a concave curved surface, or it can be a plane mirror or a concave mirror. The second reflector 21 uses its reflective surface to cause total internal reflection of the display light 11 emitted from the display device 30 toward the first reflector 20. A reflective layer can also be formed on the reflective surface of the second reflector 21 by vapor deposition or the like. In addition, by using a concave mirror for the second reflector 21, a cross-light path can be formed between the first reflector 20 and the second reflector 21. That is, the display light 11 reflected by the second reflector 21 can also cross at the intersection point 13 and be reflected by the first reflector 20 to reach the windshield WS. If such a cross-light path design can be adopted in the vehicle display device 1, then there is no need to set space in the light path. Therefore, as will be described later, by combining this with the fact that there is no need to set space inside the vehicle display device 1 for the drive reflectors 20 and 21 in order to prevent external light 12 from entering the display unit 32, it is possible to further improve the space-saving of the interior of the vehicle display device 1.

[0034] like Figures 2-6 As shown, in the optical path of the display light 11 between the reflectors 20 and 21 and the display unit 32, a liquid crystal panel 33 is arranged between the first polarizing plate 34 and the second polarizing plate 35, and the polarization direction is switched by applying voltage.

[0035] The liquid crystal panel 33 is sandwiched between the first polarizing plate 34 and the second polarizing plate 35. Specifically, as follows: Figure 5 As shown, a first polarizing plate 34, which allows one type of polarized light (P-polarized light or S-polarized light) to pass through, is disposed on the upper surface of the liquid crystal panel 33, and a second polarizing plate 35, which allows the other type of polarized light (P-polarized light or S-polarized light) to pass through, is disposed on the lower surface of the liquid crystal panel 33. The liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35 can also be configured such that the second polarizing plate 35, the liquid crystal panel 33, and the first polarizing plate 34 are stacked in that order from bottom to top, and supported on the upper part of the display unit 32 by a mounting member 37. Alternatively, the liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35 can also be supported on the frame 50 in the manner described above.

[0036] In the vehicle display device 1, external light 12, such as sunlight, sometimes enters the interior of the frame 50 through the opening 60. For example... Figure 9 As shown, external light 12 enters the frame 50 through the opening 60, is reflected and focused by the first reflecting mirror 20, which functions as a magnifying glass, and then passes through the second reflecting mirror 21 toward the display device 30. That is, the liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35 is disposed not only in the optical path of the display light 11, but also in the optical path of the external light 12.

[0037] As described above, the liquid crystal panel 33 can switch the polarization direction by applying a voltage. Figure 7 and Figure 8 This diagram compares the transmission of external light 12 through the liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35, with and without voltage applied to the liquid crystal panel 33. Here, it is explained that one polarized light is set as P-polarized light and the first polarizing plate 34 allows P-polarized light to pass through, and the other polarized light is set as S-polarized light and the second polarizing plate 35 allows S-polarized light to pass through. However, the settings for P-polarized light and S-polarized light can also be reversed.

[0038] like Figure 7 As shown, when no voltage is applied to the liquid crystal panel 33, the external light 12 first passes through the first polarizing plate 34, which has a longitudinal polarization direction, and is thus polarized longitudinally. Afterwards, although the external light 12 passes through the liquid crystal panel 33, it cannot pass through because its polarization direction is different from that of the second polarizing plate 35, which has a transverse polarization direction. Therefore, the P-polarized and S-polarized light components of the external light 12 are blocked by the first polarizing plate 34 and the second polarizing plate 35, and thus the external light 12 does not reach the display unit 32. Furthermore, regarding the display light 11 emitted through the display unit 32, the P-polarized and S-polarized light components are also blocked by the first polarizing plate 34 and the second polarizing plate 35, and therefore, like the external light 12, it cannot pass through.

[0039] On the other hand, such as Figure 8 As shown, when a voltage is applied to the liquid crystal panel 33, the external light 12 first passes through the first polarizer 34, which has a longitudinal polarization direction, and is thus polarized longitudinally. Then, in the liquid crystal panel 33, by applying a voltage, the polarization direction is switched to be aligned with the direction of the other light component, i.e., the lateral polarization direction. Therefore, the external light 12 has the same polarization direction as the second polarizer 35, which has a lateral polarization direction, and can thus pass through. Then, the external light 12 reaches the display unit 32. Furthermore, for the display light 11 emitted through the display unit 32, similarly to the external light 12, the light component with the polarization direction of either P-polarized light or S-polarized light can pass through.

[0040] Therefore, by setting the display of the vehicle display device 1 to off, and by setting it to a state where no voltage is applied to the liquid crystal panel 33, external light 12 will not reach the display unit 32, thus preventing external light 12 from incident on the display unit 32. Conventionally, to prevent external light 12 from incident on the display unit 32, a method was used to adjust the reflection angle of the external light 12 by driving reflectors 20 and 21, particularly the first reflector 20. In the vehicle display device 1 of this embodiment, external light 12 can be prevented from incident on the display unit 32 without driving reflectors 20 and 21. Furthermore, since there is no need to provide space for driving reflectors 20 and 21 inside the vehicle display device 1, space saving inside the vehicle display device 1 can be expected.

[0041] As described above, regarding the display light 11, since the display of the vehicle display device 1 is turned off and no voltage is applied to the liquid crystal panel 33, it also becomes a state where it cannot pass through, just like the external light 12. Therefore, by switching the display of the vehicle display device 1 on / off as the vehicle power supply is switched on / off, the transmission control of the display light 11 can also be performed.

[0042] In the liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35, the second polarizing plate 35 is positioned closest to the display unit 32. However, it is preferable to provide a gap S in the optical path of the display light 11 between the second polarizing plate 35 and the display unit 32. The display unit 32, like the liquid crystal panel 33, is a component that operates by applying voltage. Therefore, if the second polarizing plate 35 and the display unit 32 are arranged in an overlapping configuration, not only is light-gathering heat based on the external light 12 applied, but also heat generated by voltage application, potentially causing a temperature rise in the display unit 32. Therefore, by providing a gap S between the second polarizing plate 35 and the display unit 32, the vehicle display device 1 can create a space above the display unit 32, thus reducing heat accumulation in the display unit 32 even when the display of the vehicle display device 1 is turned on.

[0043] To create a gap S between the second polarizing plate 35 and the display unit 32, a buffer member 36 is preferably arranged around the optical path of the display light 11 between the second polarizing plate 35 and the display unit 32. The shape and material of the buffer member 36 are not particularly limited; it can be a frame or pad placed on the periphery of the display unit 32. Alternatively, the buffer member 36 can also be a component placed on the periphery of the display unit 32 during the assembly process of the second polarizing plate 35, the liquid crystal panel 33, and the first polarizing plate 34 in the upper part of the display unit 32. Figure 6As shown, by arranging a buffer member 36 at the periphery of the display unit 32 and then using a mounting member 37, the display unit 32 can be supported in a manner where, from bottom to top, the second polarizing plate 35, the liquid crystal panel 33, and the first polarizing plate 34 are stacked in that order. Furthermore, if the buffer member 36 is a heat-dissipating component, the effect of preventing temperature rise in the display unit 32 can be further improved.

[0044] Alternatively, as a buffer component 36, an additional structure can be provided on the display device 30, such as a frame-shaped spacer. Alternatively, the structure can be added to the frame of the display device 30. That is, it can be a structure added as a spacer during the manufacturing of the display device 30 in a factory, or it can be a structure pre-assembled during the assembly of the upper part of the display section 32 in the order of the second polarizing plate 35, the liquid crystal panel 33, and the first polarizing plate 34.

[0045] like Figure 9 As shown, external light 12 is focused by reflection from the first reflector 20 and then directed toward the display device 30 via the second reflector 21. In the case where only the display section 32 is positioned at the top, as in conventional display devices, the focal point of the concave mirror is located on the display section 32, therefore... Figure 10 As shown, external light 12 is focused onto the display unit 32. In the vehicle display device 1 of this embodiment, a liquid crystal panel 33 is disposed on the upper part of the display unit 32, sandwiched between the first polarizing plate 34 and the second polarizing plate 35. Therefore, as shown... Figure 11 As shown, the area L of the external light 12 incident on the uppermost part of the display device 30 becomes larger. Therefore, compared with the case where only the display section 32 is provided, the heat concentrated towards the display section 32 can be reduced. When a liquid crystal panel 33 is disposed between the first polarizing plate 34 and the second polarizing plate 35 with a gap S provided in the upper part of the display section 32, as... Figure 12 As shown, the area L of the external light 12 incident on the uppermost part of the display device 30 is further increased, which can further reduce the concentrated heat of the light on the display section 32. In this way, by providing a gap S between the second polarizing plate 35 and the display section 32, the vehicle display device 1 can reduce the concentrated heat of the external light 12 on the display section 32 and prevent the temperature from rising, even when the display of the vehicle display device 1 is set to ON.

[0046] As described above, the vehicle display device 1 of this embodiment includes a display device 30, which emits a display image projected onto a reflector (windshield WS) disposed in front of a vehicle occupant (driver D) as display light 11 via a display unit 32. Furthermore, the vehicle display device 1 includes at least one reflector 20, 21 that reflects the display light 11 along the optical path from the display device 30 to the reflector. A liquid crystal panel 33, whose polarization direction is switched by applying a voltage, is disposed between a first polarizing plate 34 and a second polarizing plate 35 along the optical path of the display light 11 between the reflectors 20, 21 and the display unit 32. A first polarizing plate 34, which allows one type of polarized light (P-polarized light and S-polarized light) to pass through, is disposed on the upper surface of the liquid crystal panel 33, and a second polarizing plate 35, which allows the other type of polarized light (P-polarized light and S-polarized light) to pass through, is disposed on the lower surface of the liquid crystal panel 33. By placing the liquid crystal panel 33 sandwiched between the first polarizing plate 34 and the second polarizing plate 35 on the upper part of the display unit 32, external light can be prevented from entering the display unit without driving the reflectors 20 and 21 when the display of the vehicle display device 1 is turned off.

[0047] Furthermore, since there is no need to provide space inside the vehicle display device 1 for driving the reflectors 20 and 21, space-saving can be expected inside the vehicle display device 1. Moreover, if a cross-optical path design can be adopted in the vehicle display device 1, there is no need to provide space in the optical path, so space-saving inside the vehicle display device 1 can be further improved.

[0048] Furthermore, when the display of the vehicle display device 1 is switched on / off in conjunction with the switching of the vehicle power supply, the time required to drive the reflectors 20 and 21 is not required, thus shortening the operation time.

[0049] Furthermore, by providing a gap S in the optical path of the display light 11 between the second polarizer 35 and the display section 32, the vehicle display device 1 can reduce the heat accumulation in the display section 32 and prevent temperature rise even when the display of the vehicle display device 1 is turned on. In addition, the area L of the external light 12 incident on the uppermost part of the display device 30 is increased, and the heat of light concentration is reduced, which can further reduce the heat accumulation in the display section 32.

[0050] The foregoing has described several embodiments of the present invention, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are also included in the scope of the invention described in the claims and its equivalents.

Claims

1. A display device for a vehicle, characterized in that, have: The display device emits a display image projected onto a reflector positioned in front of the vehicle occupants as display light via a display section. as well as At least one reflector reflects the display light in the optical path from the display device to the reflector. In the optical path of the display light between the reflector and the display unit, a liquid crystal panel whose polarization direction can be switched by applying a voltage is disposed between a first polarizing plate and a second polarizing plate. A first polarizing plate, which allows one of P-polarized light and S-polarized light to pass through, is disposed on the upper surface of the liquid crystal panel. A second polarizing plate is disposed on the lower surface of the liquid crystal panel to allow transmission of another polarized light, either P-polarized light or S-polarized light.

2. The vehicle display device according to claim 1, characterized in that, At least one of the reflectors includes a first reflector and a second reflector. The first reflecting mirror is a concave mirror. The second reflecting mirror is a plane mirror or a concave mirror.

3. The vehicle display device according to claim 1 or 2, characterized in that, A gap is provided in the optical path of the display light between the second polarizing plate and the display unit.

4. The vehicle display device according to claim 3, characterized in that, A buffer component is disposed around the optical path of the display light between the second polarizing plate and the display unit.

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