JPWO2019102775A1 - Head-up display device - Google Patents

Abstract

Provided is a head-up display device capable of allowing a viewer to visually recognize the display light even when wearing polarized sunglasses. The head-up display device 10 reflects the display light L representing the image emitted by the display 20 by the reflecting unit 30, emits the display light L reflected by the reflecting unit 30 from the emitting unit 41, and is in front of the viewer M. A head-up display device 10 that is visually recognized by a phantom image V. The emitting unit 41 includes a translucent synthetic resin sheet 50, and the synthetic resin sheet 50 has a straight line as the display light L emitted by the display 20. Polarized light is incident, and the synthetic resin sheet 50 has a phase difference function of emitting the incident linearly polarized light as circularly polarized light or randomly polarized light, and emits display light L as circularly polarized light or randomly polarized light from the emitting unit 41.

Description

The present invention relates to a head-up display device.

In a conventional head-up display device, for example, as disclosed in Patent Document 1, the display light representing an image emitted from a display is magnified by a concave mirror, and the magnified display light is irradiated to the windshield. By receiving the display light reflected on the windshield, the viewer (driver) can visually recognize the virtual image by the display light superimposed on the background seen through the windshield.

Japanese Unexamined Patent Publication No. 2006-91489

The head-up display device described in Patent Document 1 includes a liquid crystal display in which a liquid crystal display element is sandwiched between two polarizing plates as a display. The display light from this liquid crystal display is usually set to be emitted as an S-polarized component of linearly polarized light by a polarizing plate.
On the other hand, polarized sunglasses are generally configured to visually recognize the P-polarized component of linearly polarized light and cut the S-polarized component due to its function.
Therefore, when the viewer wears polarized sunglasses, the display light in the head-up display device does not pass through the polarized sunglasses, and the virtual image due to the display light cannot be visually recognized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a head-up display device capable of allowing a viewer to visually recognize the display light even when wearing polarized sunglasses.

In order to achieve the above object, the head-up display device of the present invention
A head-up display device that reflects display light representing an image emitted by a display unit at a reflecting unit, and emits the display light reflected by the reflecting unit from an emitting unit to visually recognize it by a virtual image in front of the viewer.
The exit portion includes a translucent synthetic resin sheet.
Linearly polarized light emitted from the display as the display light is incident on the synthetic resin sheet.
The synthetic resin sheet has a phase difference function of emitting the incident linearly polarized light as circularly polarized light or randomly polarized light.
The display light as the circularly polarized light or the randomly polarized light is emitted from the emitting unit.
It is characterized by that.

According to the present invention, the display light can be visually recognized even when wearing polarized sunglasses.

It is a schematic block diagram of the vehicle which mounted the head-up display device which concerns on one Embodiment of this invention. It is a schematic block diagram which concerns on one Embodiment of this invention. It is sectional drawing of the synthetic resin sheet which concerns on one Embodiment of this invention. It is sectional drawing of the synthetic resin sheet which concerns on another Embodiment of this invention.

Hereinafter, an embodiment of the head-up display device according to the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the head-up display device 10 according to the present embodiment is installed, for example, in the dashboard of the vehicle 1. The head-up display device 10 emits display light L representing an image toward the windshield 2 of the vehicle 1 from the exit portion 41 of the case 40. The viewer M (mainly the driver of the vehicle 1) receives the display light L reflected by the windshield 2 and visually recognizes the virtual image V superimposed on the background seen through the windshield 2.

As shown in FIG. 2, the head-up display device 10 includes a display 20, a reflection unit 30, and a case 40, and the case 40 includes an exit unit 41.

The display 20 is composed of a liquid crystal display, and includes a liquid crystal display panel 21, a light emitting element 22, and a wiring board 23. The liquid crystal display panel 21 has a liquid crystal cell 21a in which a liquid crystal is enclosed in a pair of translucent substrates on which a transparent electrode film is formed, a polarizing plate 21b attached to the front surface of the liquid crystal cell 21a, and a rear surface of the liquid crystal cell 21a. It is composed of the attached polarizing plate 21c and is held by the case body 24. The light emitting element 22 is arranged behind the liquid crystal display panel 21 and transmits and illuminates the liquid crystal display panel 21. The light emitting element 22 is mounted on the wiring board 23. The case body 24 has a substantially square tube shape, and the rear end portion of the case body 24 is fixed to a heat radiating member (not shown) so that heat can be dissipated.

The reflecting unit 30 includes a plane mirror 31 and a concave mirror 32. The plane mirror 31 is fixed to the case 40 via a support member. The display light L representing the image emitted from the liquid crystal display panel 21 is reflected by the plane mirror 31 and emitted toward the concave mirror 32.

The concave mirror 32 is formed by depositing a metal (for example, aluminum) on a resin (for example, polycarbonate) to form a concave reflecting surface. The concave mirror 32 is adhered to a mirror holder (not shown) with a double-sided adhesive tape. The concave mirror 32 magnifies the display light L reflected by the plane mirror 31, and can display the magnified virtual image V. The concave mirror 32 is provided with an angle adjusting mechanism, is driven by a gear and a stepping motor via a mirror holder, and is supported by the case 40 so that the angle of the concave mirror 32 can be adjusted.
As a result, the viewer M adjusts the angle of the concave mirror 32 so that the display light L representing the image is reflected at the position of the eyes (that is, the virtual image V can be visually recognized) by operating a push button switch or the like.

The case 40 is made of resin (for example, polypropylene) and houses constituent devices such as a display 20 and a reflecting unit 30. In the case 40, an open exit portion 41 is formed on the upper surface of which the display light L emitted by the display 20 is emitted, and the display light L is emitted toward the windshield 2 through the emission portion 41. .. A synthetic resin sheet 50 that functions as a cover glass is attached so as to close the opening constituting the exit portion 41. The synthetic resin sheet 50 will be described later.
Although not shown, the case 40 houses a circuit board. A drive circuit for driving the liquid crystal display panel 21 and a drive circuit for driving the light emitting element 22 are mounted on the circuit board. The circuit board and the wiring board 23 of the liquid crystal display panel 21 are electrically connected by a wiring member.

In the head-up display device 10 configured in this way, the display light L representing the image emitted from the liquid crystal display panel 21 is linearly polarized by the polarizing plate 21b attached to the front surface of the liquid crystal cell 21a, and the S polarization component. The display light L is. The display light L is reflected by the plane mirror 31 of the reflecting portion 30, and is further emitted from the opening exit portion 41 of the case 40 via the concave mirror 32.
Therefore, since the display light L emitted from the emitting unit 41 is a linearly polarized S-polarized component, the viewer M is blocked from the S-polarized component when wearing polarized sunglasses G. The virtual image V cannot be visually recognized.
Therefore, a synthetic resin sheet 50 is provided at the exit portion 41 of the case 40, and the linearly polarized light L is polarized into circularly polarized light or randomly polarized light by the phase difference function.

The synthetic resin sheet 50 has a phase difference function of converting linearly polarized light into circularly polarized light or randomly polarized light in the synthetic resin sheet itself, and has the same function as a λ / 4 plate (1/4 wave plate). It is a base material. The synthetic resin sheet 50 is a birefringent sheet that imparts a phase difference of π / 2 (90 °) between two orthogonal polarizing components to the light transmitted through the synthetic resin sheet 50. As a result, the light transmitted through the synthetic resin sheet 50 is out of phase by π / 2 before and after the transmission. The synthetic resin sheet 50 has a phase-advancing axis (fast axis) and a slow-phase axis (slow axis), and linearly polarized light incident on the phase-advancing axis at an angle of ± 45 ° is circularly polarized (circularly polarized light). Or randomly polarized light).
In the synthetic resin sheet 50, the angle formed by the absorption axis (axis perpendicular to the polarization axis) of the polarizing plate 21b on the front side (visual side) of the liquid crystal display panel 21 and the slow axis of the synthetic resin sheet 50 is approximately 45 °. It is attached to the exit portion 41 so as to be. This synthetic resin sheet 50 is used in place of the cover glass that covers the open exit portion 41 of the head-up display device 10. For example, the synthetic resin sheet 50 is processed into an outer shape of a quadric surface and attached around the exit portion 41 with double-sided tape or the like. Can be installed.

As the synthetic resin sheet 50, a transparent polymer sheet is used, for example, polycarbonate (PC: polycarbonate), polyethylene terephthalate (PET) is preferably used, and other polymer sheets can be used. ..
The synthetic resin sheet 50 has a high retardation, for example, a synthetic resin sheet 50 having a retardation of about 8000 nm and a thickness of 300 μm or more, more preferably 400 μm or more is used. Here, the retardation is the product of the birefringence and the thickness of the polymer sheet.
The retardation is small and does not function as a birefringent at 3000 nm. If the thickness is thinner than 300 μm, the rigidity of the cover glass cannot be ensured, and the upper limit of the thickness is set to a thickness within a range in which a double image is not generated because a double image is generated when the thickness is increased.
When the synthetic resin sheet 50 is composed of, for example, a polycarbonate sheet, the polycarbonate is melted, extruded into a sheet, and stretched in one or two directions at a temperature equal to or higher than the glass transition temperature to obtain a high retardation sheet. Can be. The retardation can be set by adjusting the stretching ratio, the stretching temperature, and the sheet thickness, and it is known that the higher the stretching ratio, the lower the stretching temperature, and the thicker the sheet, the larger the retardation.

A synthetic resin sheet 50 as such a high birefringence base material is provided in the exit portion 41, and the display light L reflected by the concave mirror 32 is transmitted through the synthetic resin sheet 50 and emitted to obtain linearly polarized light. The display light L is converted into circularly polarized (or randomly polarized) light by the phase difference function of the synthetic resin sheet 50.
As a result, the light transmitted through the synthetic resin sheet 50 becomes circularly polarized light or randomly polarized light, is reflected by the front glass 2, and reaches the viewer M, and even if the polarized sunglasses G are worn, the virtual image V Can be seen unobstructed.
Further, by using a synthetic resin sheet 50 having a thickness of 300 μm or more, it is possible to secure the required rigidity even if it is used instead of the conventional cover glass.

The synthetic resin sheet 50 is provided with a transparent hard coat layer 51 on the emission side of the display light L, that is, on the surface located outside the case 40 (see FIG. 3). The hard coat layer 51 is formed by applying a thermosetting resin, an ultraviolet curable resin, or the like to the synthetic resin sheet 50. As a result, the surface of the synthetic resin sheet 50 can be protected from damage such as scratches.
The hard coat layer 51 is not limited to the case where the hard coat layer 51 is formed by applying a permeable resin, and another synthetic resin film may be attached and provided.
The synthetic resin sheet 50 is provided with a light-shielding printing layer 52 on the display 20 side, that is, on the surface located inside the case 40, and is provided so as to cover a region outside the visible range of the image by the display light L (). (See FIG. 3). As a result, the area other than the visible range in the case 40 is blindfolded by the print layer 52.

Further, the emitting unit 41 includes a polarizing function film 53 bonded to the display 20 side of the synthetic resin sheet 50, and the polarizing function film 53 uses the display light L emitted by the display 20 as linear polarization and is a synthetic resin sheet. It is designed to be incident on 50. That is, the synthetic resin sheet 50 has the polarizing function film 53 bonded to the display 20 side, that is, the surface located inside the case 40. The polarizing function film 53 can block stray light when stray light is emitted from the liquid crystal display panel 21 of the display 20 in addition to the linearly polarized S polarization component, and can prevent the generation of a ghost image. Further, it is necessary to arrange the display light L reflected by the concave mirror 32 so that the angle formed by the slow axis of the synthetic resin sheet 50 is approximately 45 °, but the polarizing function film 53 is previously provided on the synthetic resin sheet 50. The delay angle can be adjusted by providing the head-up display device 10, and the head-up display device 10 can be easily assembled.
Further, the polarizing function film 53 has a function of cutting (preventing) the incident of sunlight into the case 40.

When the polarizing function film 53 is provided, as shown in FIG. 4, the print layer 52 is provided so as to cover the area other than the visible range of the polarizing function film 53. In this case, it is not necessary to provide the polarizing function film 53 on top of the printing layer 52, and the polarizing function film 53 is attached to the inside of the printing layer 52. As a result, by attaching the polarizing function film 53 to the inside of the print layer 52, the polarizing function film 53 can be made smaller than that provided on the entire surface of the synthetic resin sheet 50.
Although not shown, the print layer 52 may be provided between the synthetic resin sheet 50 and the polarizing function film 53.

As described above, as described specifically with the embodiment, according to the head-up display device 10 of the present invention, the display light L representing the image emitted by the display 20 is reflected by the reflecting unit 30 and reflected by the reflecting unit 30. A head-up display device 10 for emitting the displayed light L from the emitting unit 41 and visually recognizing it by a virtual image V in front of the viewer M. The emitting unit 41 includes a synthetic resin sheet 50 having translucency and is synthesized. The resin sheet 50 is incident with linearly polarized light as the display light L emitted by the display 20, and the synthetic resin sheet 50 has a phase difference function of emitting the incident linearly polarized light as circularly polarized light or randomly polarized light. Since the display light L as circularly polarized light or randomly polarized light is emitted from the unit 41, the linearly polarized light indicating light L is converted into circularly polarized light (or randomly polarized light) by the phase difference function of the synthetic resin sheet 50. As a result, the light transmitted through the synthetic resin sheet 50 becomes circularly polarized light or randomly polarized light, is reflected by the front glass 2, and reaches the viewer M, and even if the polarized sunglasses G are worn, the virtual image V Can be visually recognized without being blocked.
Further, since the synthetic resin sheet 50 alone has a retardation function, it can be made thinner than the conventional case where the retardation plate is laminated on the base sheet, and it depends on the variation in the optical characteristics of each layer. It is possible to suppress the influence of variations in brightness and transmittance and improve visibility by wearing polarized sunglasses G.

According to the head-up display device 10 of the present invention, the exiting portion 41 includes a polarizing function film 53 bonded to the display 20 side of the synthetic resin sheet 50, and the polarizing function film 53 is a display emitted by the display 20. Since the light L is linearly polarized and incident on the synthetic resin sheet 50, when stray light is emitted from the display 20, the stray light can be blocked, the generation of ghost images can be prevented, and visibility by wearing polarized sunglasses can be improved. Can be improved.
Further, it is necessary to arrange the display light L from the display 20 so that the angle formed by the slow axis of the synthetic resin sheet 50 is approximately 45 °, but the polarizing function film 53 is previously attached to the synthetic resin sheet 50. By providing the head-up display device 10, the retard phase angle can be adjusted in advance, and the head-up display device 10 can be easily assembled.

According to the head-up display device 10 of the present invention, since the synthetic resin sheet 50 has a thickness of 300 μm or more, it has high rigidity and durability even if it is thin, and it is necessary to use it in place of the conventional glass cover. Rigidity and durability can be ensured, generation of double images can be suppressed, and visibility can be improved by wearing polarized sunglasses.

According to the head-up display device 10 of the present invention, since the hard coat layer 51 is provided on the emission side of the display light L of the synthetic resin sheet 50, the surface of the synthetic resin sheet 50 can be protected to cause scratches. Damage can be prevented, visibility and durability can be improved, and visibility can be improved by wearing polarized sunglasses.

According to the head-up display device 10 of the present invention, the light-shielding printing layer 52 located on the display 20 side of the synthetic resin sheet 50 is provided, and the printing layer 52 corresponds to the outside of the visible range of the image represented by the display light L. Since the area is provided in the area to be used, the area of the synthetic resin sheet 50 that is not necessary for visual recognition can be blinded by the printing layer 52, and the visible range required for the head-up display device 10 can be clarified. Visibility can be improved by wearing sunglasses.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, the synthetic resin sheet 50 is not limited to the case of being formed by a quadric surface, and may be flat. ..

In the above embodiment, the case where the head-up display device 10 is mounted on a vehicle has been described as an example, but the head-up display device 10 may be mounted on a vehicle such as an airplane or a ship, not limited to the vehicle.

1 Vehicle 2 Front glass 10 Head-up display device 20 Display 21 Liquid crystal display panel 21a Liquid crystal cell 21b Polarizing plate 21c Polarizing plate 22 Light emitting element 23 Wiring board 24 Case body 30 Reflecting part 31 Plane mirror 32 Concave mirror 40 Case 41 Exiting part 50 Synthetic resin Sheet 51 Hard coat layer 52 Printing layer 53 Polarizing function film G Polarized sunglasses L Display light M Viewer V Virtual image

Claims (5)

A head-up display device that reflects display light representing an image emitted by a display unit at a reflecting unit, and emits the display light reflected by the reflecting unit from an emitting unit to visually recognize it by a virtual image in front of the viewer.
The exit portion includes a translucent synthetic resin sheet.
Linearly polarized light emitted from the display as the display light is incident on the synthetic resin sheet.
The synthetic resin sheet has a phase difference function of emitting the incident linearly polarized light as circularly polarized light or randomly polarized light.
The display light as the circularly polarized light or the randomly polarized light is emitted from the emitting unit.
A head-up display device characterized by this. The emitting portion includes a polarizing functional film attached to the display side of the synthetic resin sheet.
In the polarizing function film, the display light emitted by the display is used as the linearly polarized light and is incident on the synthetic resin sheet.
The head-up display device according to claim 1. The synthetic resin sheet has a thickness of 300 μm or more.
The head-up display device according to claim 1 or 2. A hard coat layer is provided on the emission side of the display light of the synthetic resin sheet.
The head-up display device according to any one of claims 1 to 3. A light-shielding printing layer located on the display side of the synthetic resin sheet is provided.
The print layer is provided in a region corresponding to a region outside the visible range of the image represented by the display light.
The head-up display device according to any one of claims 1 to 4.

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