Vehicular projection device

Abstract

To provide a vehicular projection device which can achieve visibility of images and aesthetic quality of a vehicle.SOLUTION: A vehicular projection device 1 is mounted on a vehicle and includes: a projector 10 which emits display light PL; a screen 20 having a transmission layer in which a transmission rate of the display light PL varies, and a reflection layer which reflects the display light PL which is transmitted through the transmission layer to cause a viewer 5 to view the display light PL; and a transmission rate control unit 30 which sets the transmission rate of the transmission layer to a first transmission rate when the display light PL is emitted from the projector 10 and sets the transmission rate of the transmission layer to a second transmission rate lower than the first transmission rate when the display light PL is not emitted from the projector 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a projection device for a vehicle.

Background Art

[0002] Conventionally, there has been known a technique of projecting an image projected from a projector installed inside a vehicle onto a screen arranged on an instrument panel or the like inside the vehicle to provide necessary information to passengers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When trying to improve the visibility of the image projected onto the screen, in order to improve the reflectivity of the screen, it is preferable that the screen itself has a light color such as white or silver. However, there may be a lack of unity in the color tone with the vehicle interior such as the instrument panel, and there is a risk of impairing the appearance.

[0005] The present disclosure has been made in consideration of such circumstances, and an object thereof is to provide a projection device for a vehicle that can achieve both visibility of an image and appearance of the vehicle.

Means for Solving the Problems

[0006] The vehicle projection device of the present disclosure is a vehicle projection device mounted on a vehicle in order to solve the above-described problems, and includes a projector that emits display light, a transmissive layer whose light transmittance is variable, and a transmissive layer. A screen having a reflective layer that reflects the display light transmitted through the layer and allows a viewer to view it, and when the display light is emitted from the projector, the transmittance of the transmissive layer is set to a first transmittance, and when the display light is not emitted from the projector, the transmittance of the transmissive layer is set to a second transmittance lower than the first transmittance, and a transmittance control unit.

Advantages of the Invention

[0007] In the vehicle projection device of the present disclosure, it is possible to achieve both visibility of an image and the appearance of a vehicle.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Embodiments of the vehicle projection device of the present disclosure will be described with reference to the accompanying drawings. The vehicle projection device of the present disclosure can be applied to any vehicle such as an automobile, an agricultural machine, and a construction machine. In the present embodiment, an example in which the vehicle projection device is mounted on an automobile will be used for explanation.

[0010] FIG. 1 is an explanatory diagram conceptually showing a configuration example of the vehicle projection device 1 according to the present embodiment.

[0011] The vehicle projection device 1 (hereinafter referred to as "projection device 1") emits display light PL and allows a viewer 5 (a passenger) inside the vehicle to view an image related to the display light PL reflected by the screen 20. The projection device 1 mainly includes a projector 10, a screen 20, and a control unit (transmittance control unit) 30.

[0012] The projector 10 is a known projector having a light source of single color or multiple colors, an optical system, a display panel, a control circuit, etc. The projector 10 emits (projects) display light PL related to an image toward the screen 20. The projector 10 displays various information such as vehicle information necessary for driving and images for entertainment. The projector 10 is disposed at a position where it can project onto the screen 20, and is attached, for example, to the roof 3 of the vehicle 2, a pillar, a center console, or the vicinity thereof.

[0013] The screen 20 is fixed to an interior part of the vehicle 2 at a position where the viewer 5 can view it, and is disposed, for example, on the instrument panel (or dashboard) 4. Here, FIG. 2 is a cross-sectional view for explaining the layer configuration of the screen 20. The screen 20 has a base material 21, a reflective layer 22, a diffusion layer 23, a liquid crystal layer (transmission layer) 24, and a pretreatment layer 25 from the side opposite to the viewer 5. Each layer is adhered by a colorless and transparent adhesive layer.

[0014] The base material 21 is a thin sheet member made of a synthetic resin having translucency (for example, PMMA, acrylic, polycarbonate (PC), polyethylene terephthalate (PET)). The base material 21 contains a light-absorbing black pigment so as to absorb the incoming light, or has a black paint or black printing on the front surface of the sheet member.

[0015] The reflective layer 22 is a layer having a high reflectivity that reflects the display light PL transmitted through the liquid crystal layer 24 etc. and allows the viewer 5 to view it. The reflective layer 22 is formed in a substantially mirror-like shape by metal vapor deposition, high-brightness painting, etc.

[0016] When the reflective layer 22 is formed by metal vapor deposition, the reflective layer 22 has a substrate, an undercoat layer, a vapor deposition layer, and a topcoat layer. The substrate is made of, for example, PET or PC. The undercoat layer functions to improve the adhesion of the metal vapor deposition layer and is made of, for example, a UV-curable or thermosetting hard coat. It is applied and formed on the substrate of the reflective layer 22 using a coating means. The metal vapor deposition layer is made of an alloy mainly composed of silver or aluminum and has optical characteristics of high reflectivity at each wavelength component in the visible light band (wavelength 380 to 780 nm). The topcoat layer functions as a protective layer that acts to prevent corrosion of the metal vapor deposition layer.

[0017] When the reflective layer 22 is formed by high-brightness painting, the reflective layer 22 has a substrate and a painted layer. The substrate is made of, for example, PET or PC. The painted layer is a layer on which a paint with high light reflectivity is painted or printed on the substrate. The paint contains, for example, aluminum powder or foil as the main raw material and contains thin flaky pigments that have been pulverized and polished.

[0018] The diffusion layer 23 is a film that diffuses the transmitted light, and various known films can be used. For example, the diffusion layer 23 is of the bead coating type, emboss type, columnar structure type, etc.

[0019] The bead coating type diffusion layer 23 is formed by coating an inorganic compound such as barium sulfate or titanium oxide on a transparent substrate of PET or PC using a binder resin. The bead coating type diffusion layer 23 preferably has diffusion characteristics close to complete diffusion.

[0020] The emboss type diffusion layer 23 is formed by forming a random uneven shape on a transparent substrate of an amorphous resin such as PC. The emboss type diffusion layer 23 has high transmittance and diffusion characteristics with directivity.

[0021] The diffusion layer 23 of the columnar structure type is one in which fine columnar structures are oriented and dispersed in a certain direction in the thickness direction within a transparent base material such as PET. The diffusion layer 23 of the columnar structure type has high transparency and has a diffusion characteristic of selectively scattering only incident light within a specific angular range.

[0022] The liquid crystal layer 24 functions as a transmissive layer with a variable transmittance of the display light PL. The liquid crystal layer 24 is, for example, a polymer dispersed liquid crystal element in which liquid crystals are dispersed in a polymer and which does not require a polarizing element. Since the polymer dispersed liquid crystal element can have a two-dimensional curved surface shape or an irregular shape, it can have a high degree of freedom in the placement location of the screen 20 and a high degree of freedom in the shape of the screen itself.

[0023] The liquid crystal layer 24 contains a dye. It is preferable that the liquid crystal layer 24 is color-adjusted so that the appearance of the screen 20 composed of the base material 21 to the pretreatment layer 25 has a color tone substantially the same as that of the instrument panel 4 where the screen 20 is placed, for example, black.

[0024] When no electric field is applied, the liquid crystal elements in the liquid crystal layer 24 are in a state of being unevenly oriented. For this reason, the liquid crystal layer 24 becomes opaque and scatters the transmitted light. Also, the dyes mixed in the liquid crystal layer 24 are similarly unevenly oriented. As a result, in the liquid crystal layer 24, the transmittance of visible light decreases to, for example, 5% or less, and is visually recognized by the viewer 5 as the color of the dye, which is black. On the other hand, when an electric field is applied, the liquid crystal elements in the liquid crystal layer 24 are in a state of being oriented in the electric field direction. For this reason, the liquid crystal layer 24 becomes transparent and transmits light. Also, the dyes mixed in the liquid crystal layer 24 are similarly oriented in the electric field direction. As a result, in the liquid crystal layer 24, the transmittance of visible light can be 40% or more, and is visually recognized by the viewer 5 as a light gray color with the color of the dye being lighter.

[0025] The pretreatment layer 25 applies a hard coat to the surface (incident surface) of the liquid crystal layer 24 on the side opposite to the surface of the base material 21 for the purpose of enabling the screen 20 to have required scratch resistance. Further, the pretreatment layer 25 may be provided with an AG (Anti-Glare) coating or an AR (Anti-Reflection) coating (non-reflection), or both coatings, in order to reduce the reflection of unintended light onto the screen 20. The pretreatment layer 25 is formed by painting, printing, vapor deposition, sputtering, or the like. Further, the pretreatment layer 25 may be formed by attaching a film having the above functions to the liquid crystal layer 24 with a transparent double-sided adhesive film or an adhesive.

[0026] The control unit 30 is connected to the control circuit of the projector 10 and the liquid crystal layer 24, and controls the transmittance of the liquid crystal layer 24 according to the state of the projector 10. Specifically, when the display light PL is emitted from the projector 10, the control unit 30 controls to apply an electric field to the liquid crystal layer 24, and causes the display light PL to pass through the liquid crystal layer 24 (the transmittance is set to the first transmittance). On the other hand, when the display light PL is not emitted from the projector 10, the control unit 30 controls not to apply an electric field to the liquid crystal layer 24, and causes the display light PL to be reflected and absorbed in the liquid crystal layer 24, thereby making the display light PL substantially non-transmissive (the transmittance is set to a second transmittance lower than the first transmittance). Although it is preferable that the liquid crystal layer 24 makes the display light PL non-transmissive as much as possible, it is also acceptable if a slight amount of the display light PL that is not visible to the viewer 5 passes through.

[0027] Next, the operation when the projection device 1 projects an image will be described.

[0028] The projector 10 emits display light PL related to an image at a required timing, for example, based on the control of the control unit 30. Further, when display is not required, the projector 10 does not emit the display light PL. The control unit 30 controls the application state of the electric field to the liquid crystal layer 24 in conjunction with the presence or absence of display on the projector 10. Specifically, at the timing when the projector 10 displays an image, the control unit 30 applies an electric field to the liquid crystal layer 24, and the liquid crystal layer 24 enters a transmission state in which light passes through.

[0029] Here, FIG. 3 is a cross-sectional view for explaining the screen 20 when the liquid crystal layer 24 is in an opaque state. FIG. 4 is an explanatory view of the screen 20 and the instrument panel 4 when the liquid crystal layer 24 is in an opaque state.

[0030] As described above, when no electric field is applied, the liquid crystal layer 24 has substantially the same color tone as the instrument panel 4 on which the screen 20 is disposed, as shown in FIG. 4. Therefore, it can be integrated with the instrument panel 4 so that the viewer 5 is not aware that the screen 20 is disposed or does not feel a sense of discomfort. Further, the appearance of the instrument panel 4 is not impaired by disposing the screen 20.

[0031] In addition, since the liquid crystal layer 24 is in an opaque state that does not transmit light, even when unintended light such as external light is projected onto the screen 20, the transmission of the light through the liquid crystal layer 24 can be suppressed. For this reason, without the external light being diffused by the diffusion layer 23 or reflected by the reflection layer 22, the color tone of the screen 20 can be visually recognized as the color tone of the liquid crystal layer 24.

[0032] On the other hand, when the projector 10 displays an image, the control unit 30 applies an electric field to the liquid crystal layer 24 to uniformly orient the liquid crystal elements and the dyes. Here, FIG. 5 is a cross-sectional view for explaining the screen 20 when the liquid crystal layer 24 is in a transmissive state. FIG. 6 is an explanatory view of the screen 20 and the instrument panel 4 when the liquid crystal layer 24 is in a transmissive state.

[0033] As shown in FIG. 6, the liquid crystal layer 24 has the contained dyes visually recognized thinner than when no voltage is applied. Further, the display light PL emitted from the projector 10 sequentially passes through the pretreatment layer 25, the liquid crystal layer 24, and the diffusion layer 23 and reaches the reflection layer 22 as shown in FIG. 5. Then, the display light PL is reflected by the reflection layer 22 and reaches the viewer 5, thereby allowing the image 28 to be visually recognized.

[0034] Such a projection device 1 can achieve both visibility during image 28 display and appearance during non-display by having a liquid crystal layer 24 that can control the presence or absence of transmission of display light PL. That is, when the projection device 1 displays the image 28 by the projector 10, it can surely guide the display light PL to the reflection layer 22, suppress a decrease in screen gain, and allow the viewer 5 to view a bright image 28. Further, when the image 28 is not being displayed, the projection device 1 can enhance the color tone unity with the interior members of the vehicle 2 because color tones such as white and silver from the reflection layer 22 are not exposed, and can make the presence of the screen 20 less noticeable.

[0035] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

[0036] For example, the driving method of the liquid crystal element can be applied in either the normal mode or the reverse mode. In the case of the reverse mode, the relationship between the electric field and the transmission state is reversed from that in the normal mode. That is, light is transmitted when no electric field is applied, and non-transmitted when an electric field is applied.

Explanation of Reference Numerals

[0037] 1 Vehicle-mounted projection device (projection device) 2 Vehicle 3 Roof 4 Instrument panel 5 Viewer 10 Projector 20 Screen 21 Base material 22 Reflection layer 23 Diffusion layer 24 Liquid crystal layer (transmission layer) 25 Pretreatment layer 28 images 30 Control unit (transmittance control unit) PL display light

Claims

1. A vehicle-mounted projection device for a vehicle, comprising: a projector that emits display light; a screen having a transmissive layer with a variable transmittance of the display light, and a reflective layer that reflects the display light transmitted through the transmissive layer and allows a viewer to view it; a transmittance control unit that sets the transmittance of the transmissive layer to a first transmittance when the display light is emitted from the projector, and sets the transmittance of the transmissive layer to a second transmittance lower than the first transmittance when the display light is not emitted from the projector.

2. The vehicle-mounted projection device according to claim 1, wherein the second transmittance is a transmittance that makes the display light substantially non-transmissive.

3. The vehicle-mounted projection device according to claim 1, wherein the transmissive layer has a color tone substantially the same as the location where the screen is disposed when the transmittance is the second transmittance.

4. The vehicle-mounted projection device according to claim 1, wherein the screen is disposed on an instrument panel of the vehicle.

Images