EP-4737989-A1 - DISPLAY DEVICE

Abstract

A display device capable of displaying an aerial image by using retroreflection is provided. The display device includes: a light source; a retroreflective member; a first polarizing beam splitter configured to reflect light from the light source toward the retroreflective member; a retardation plate disposed between the first polarizing beam splitter and the retroreflective member and configured to provide a constant phase difference between incident light and outgoing light; a decorative sheet configured to transmit the light of the aerial image transmitted through the first polarizing beam splitter; and a second polarizing beam splitter disposed on a bottom side of the decorative sheet that is a side opposite to a decorative surface of the decorative sheet and configured to have a transmission axis aligned in a same direction as a direction in which the light of the aerial image is transmitted.

Inventors

• ASHIMINE, KATSUNARI

Assignees

• Alps Alpine Co., Ltd.

Dates

Publication Date

20260506

Application Date

20251024

Claims (5)

1. A display device capable of displaying an aerial image by using retroreflection, the display device comprising: a light source; a retroreflective member; a first polarizing beam splitter configured to reflect light from the light source toward the retroreflective member; a retardation plate disposed between the first polarizing beam splitter and the retroreflective member and configured to provide a constant phase difference between incident light and outgoing light; a decorative sheet configured to transmit the light of the aerial image transmitted through the first polarizing beam splitter; and a second polarizing beam splitter disposed on a bottom side of the decorative sheet that is a side opposite to a decorative surface of the decorative sheet and configured to have a transmission axis aligned in a same direction as a direction in which the light of the aerial image is transmitted.
2. The display device according to claim 1, wherein the second polarizing beam splitter includes a transparent substrate and a polarizing film formed on the transparent substrate, and the polarizing film faces a bottom surface of the decorative sheet.
3. The display device according to claim 1 or 2, wherein the decorative sheet is laminated on the second polarizing beam splitter.
4. The display device according to one of claim 1 to 3, wherein the decorative sheet includes ink or paint that includes a light diffusion component.
5. The display device according to one of claim 1 to 4, wherein the retardation plate is a A/4 wave plate.

Description

The present application is based on and claims priority to Japanese Patent Application No. 2024-191532 filed on October 31, 2024, the entire contents of which are hereby incorporated by reference. The present disclosure relates to a display device for displaying an aerial image by using retroreflection. Aerial imaging by retroreflection (AIRR) is known. For example, in an aerial imaging device disclosed in Japanese Laid-Open Patent Application No. 2020-76811, a decorative sheet is disposed between an imaging element 20 and an imaging position P such that the imaging element 20 is not observed from the outside. The decorative sheet may, for example, have holes made in it or be printed with transparent ink. The present disclosure relates to a display device according to the appended claims. Embodiments are disclosed in the dependent claims. A display device according to the present disclosure is capable of displaying an aerial image by using retroreflection, and includes a light source, a retroreflective member, a first polarizing beam splitter configured to reflect light from the light source toward the retroreflective member, a retardation plate disposed between the first polarizing beam splitter and the retroreflective member and configured to provide a constant phase difference between incident light and outgoing light, a decorative sheet configured to transmit the light of the aerial image transmitted through the first polarizing beam splitter, and a second polarizing beam splitter disposed on a bottom side of the decorative sheet that is a side opposite to a decorative surface of the decorative sheet and configured to have a transmission axis aligned in the same direction as the direction in which the light of the aerial image is transmitted. FIG. 1 is a top view illustrating a schematic configuration of an existing display device for displaying an aerial image;FIG. 2 is a top view illustrating a schematic configuration of a display device according to an embodiment of the present disclosure; andFIG. 3 is a diagram illustrating a difference between the existing display device and the display device according to the embodiment of the present disclosure. FIG. 1 is a top view illustrating a schematic configuration of an existing display device for displaying an aerial image. A display device 10 is configured to include a display 20, a polarizing beam splitter 30, a λ/4 wave plate 40, a retroreflective member 50, and a decorative sheet 60 in a housing such as a casing, for example. The display 20 generates an original image of an aerial image P, and the light of the original image is emitted toward the polarizing beam splitter 30. The light output from the display 20 may be polarized light. The polarizing beam splitter 30 reflects a part of incident light toward the λ/4 wave plate 40, the light transmitted through the λ/4 wave plate 40 is reflected by the retroreflective member 50 in the same direction as the incident light, and this reflected light again transmits through the λ/4 wave plate 40 and is incident on the polarizing beam splitter 30. A transmission axis of the polarizing beam splitter 30 is aligned with a direction in which the light of the aerial image is transmitted, and the light transmitted through the polarizing beam splitter 30 forms an image of the aerial image P through the decorative sheet 60. An imaging position of the aerial image P is symmetrical to the position of the display 20 with respect to the main surface of the polarizing beam splitter 30. When the color of a decorative surface of the decorative sheet 60 is made bright in order to enhance the appearance design, it is necessary to make a layer of the ink printed on the decorative sheet 60 thick, or to increase the amount of white ink used in a light diffusion layer. That is, in order to make the decorative surface appear bright, it is necessary to increase a light diffusion component of the ink and scatter light L1 entering from the outside to a large extent by a portion printed by the ink on the decorative surface and by the light diffusion component of the ink. In contrast to this, in order to form an image of the aerial image P, it is necessary to allow light L2 of the aerial image from the polarizing beam splitter 30 to pass through the decorative sheet 60 and to converge the light externally. However, when the light diffusion component of the ink of the decorative sheet 60 is increased to increase the scattering of the light L1 entered from the outside, the scattering with respect to the light L2 of the aerial image from the inside also increases, and thus the decorative sheet 60 undesirably scatters the light L2 of the aerial image. As a result, the resolution (blur) and the luminance (brightness) of the aerial image P are reduced. The present disclosure provides a display device capable of preventing the degradation of the resolution and the luminance of the aerial image while brightening the decorative surface. Next, a