US-12625367-B2 - Air floating video display apparatus and light source

US12625367B2US 12625367 B2US12625367 B2US 12625367B2US-12625367-B2

Abstract

A compact air floating video display apparatus providing a highly visually recognized air floating video less susceptible to external light and having fewer ghosts is provided. The air floating video display apparatus includes: an opening portion having a transparent member configured to transmit video light of a specific polarization wave therethrough; a display panel serving as a video source; a light source configured to supply light having specific polarization directionality to the video source; a retroreflection optical member having a retroreflection surface provided with a waveplate; one or more reflection mirrors; a polarization splitter arranged in a space connecting the video source and the retroreflection optical member.

Inventors

Koji Hirata
Koji Fujita
Toshinori Sugiyama

Assignees

MAXELL, LTD.

Dates

Publication Date: 20260512
Application Date: 20211201
Priority Date: 20201225

Claims (20)

1 . An air floating video display apparatus forming an air floating video comprising: an opening portion configured to transmit video light of a specific polarization wave forming the air floating video therethrough; a transparent member arranged at the opening portion and configured to transmit the video light therethrough; a display panel serving as a video source; a light source configured to supply light having specific polarization directionality to the video source; a retroreflection optical member having a retroreflection surface provided with a waveplate; one or more reflection mirrors; and a polarization splitter arranged in a space connecting the video source and the retroreflection optical member, wherein the video light of the specific polarization wave emitted from the video source is once transmitted through the polarization splitter, the video light transmitted through the polarization splitter is reflected by a first reflection mirror serving as the reflection mirror toward the retroreflection optical member, the video light reflected by the first reflection mirror is converted in terms of light polarization by the retroreflection optical member to convert one polarization wave of the video light to another polarization wave, the converted video light is reflected again by the first reflection mirror, the video light reflected again by the first reflection mirror is reflected by the polarization splitter toward the opening portion, the air floating video that is an actual image based on the video light reflected by the polarization splitter is displayed outside the transparent member of the opening portion, and a forming position of the air floating video is changed by a structure changing a distance from the video source to the retroreflection optical member.
2 . The air floating video display apparatus according to claim 1 , wherein at least one reflection mirror serving as the reflection mirror is arranged in a light path connecting the air floating video and the polarization splitter, and the forming position of the air floating video is changed by turning of the at least one reflection mirror in the light path.
3 . The air floating video display apparatus according to claim 1 , wherein at least one reflection mirror serving as the reflection mirror is arranged in a light path connecting the air floating video and the polarization splitter, and a reflection mirror closest to the air floating video among the at least one reflection mirror is made of a metallic multilayer film configured to reflect the specific polarization wave of the video light but transmit another polarization wave.
4 . The air floating video display apparatus according to claim 1 , wherein the polarization splitter is made of a reflection-type light polarizer or a metallic multilayer film configured to reflect the specific polarization wave.
5 . The air floating video display apparatus according to claim 1 , wherein an absorption-type light polarizer is arranged on at least one surface of the transparent member.
6 . The air floating video display apparatus according to claim 1 , wherein, in the transparent member, a portion configured to transmit the video light therethrough is made of a transparent body, and a portion configured not to transmit the video light therethrough is made of a light block member.
7 . The air floating video display apparatus according to claim 1 , wherein an anti-reflection film is arranged on a video display surface of the display panel, an absorption-type light polarizer is arranged on the display panel, and the reflected light is absorbed by the absorption-type light polarizer.
8 . The air floating video display apparatus according to claim 1 , wherein a video displayed on the display panel is a video configured to correct a distortion of an image generated in an optical system forming the air floating video.
9 . An air floating video display apparatus forming an air floating video comprising: an opening portion configured to transmit video light of a specific polarization wave forming the air floating video therethrough; a transparent member arranged at the opening portion and configured to transmit the video light therethrough; a display panel serving as a video source; a light source configured to supply light having specific polarization directionality to the video source; a retroreflection optical member having a retroreflection surface provided with a waveplate; a plurality of reflection mirrors; and a polarization splitter arranged in a space connecting the video source and the retroreflection optical member, wherein the video light of the specific polarization wave emitted from the video source is once transmitted through the polarization splitter, the video light transmitted through the polarization splitter is reflected by a first reflection mirror of the reflection mirrors toward the retroreflection optical member, the video light reflected by the first reflection mirror is converted in terms of light polarization by the retroreflection optical member to convert one polarization wave to another polarization wave, the converted video light is reflected again by the first reflection mirror, the video light reflected again by the first reflection mirror is reflected by the polarization splitter toward the opening portion, the air floating video that is an actual image based on the video light reflected by the polarization splitter is displayed outside the transparent member of the opening portion, a forming position of the air floating video is changed by a structure changing a distance from the video source to the retroreflection optical member, a surface roughness of a reflection surface of the retroreflection optical member is set so that a ratio of a blur amount of the air floating video to a pixel size of the video source is 40% or less, the light source includes: a point-type or surface-type light source; an optical member configured to reduce a divergence angle of light emitted from the light source; a polarization converter configured to unify the light emitted from the light source to be polarization light having specific directionality; and a light guiding body having a reflection surface configured to propagate light to the video source, the video light is adjusted by a shape and a surface roughness of a reflection surface arranged on the light source, and video luminous flux having a narrow divergence angle emitted from the video source is reflected by the retroreflection optical member to aerially form the air floating video.
10 . The air floating video display apparatus according to claim 9 , wherein the surface roughness of the reflection surface of the retroreflection optical member is set to 160 nm or less, the light source includes: a point-type or surface-type light source; an optical member configured to reduce a divergence angle of light emitted from the light source; a polarization converter configured to unify the light emitted from the light source to be polarization light having a specific directionality; and a light guiding body having a reflection surface configured to propagate light to the video source, the light guiding body faces the video source, and its inside or its surface has the reflection surface configured to reflect the light emitted from the light source toward the video source, and light is propagated to the video source by the reflection surface, the video source modulates light intensity in accordance with a video signal, and the video luminous flux having a narrow divergence angle emitted from the video source is reflected by the retroreflection optical member to aerially form the air floating video.
11 . The air floating video display apparatus according to claim 9 , wherein, in the light source, a part or all of a divergence angle of luminous flux is adjusted by a shape and a surface roughness of the reflection surface of the light source so that a light beam divergence angle of the display panel is within ±30 degrees.
12 . The air floating video display apparatus according to claim 9 , wherein, in the light source, a part or all of a divergence angle of luminous flux is adjusted by a shape and a surface roughness of the reflection surface of the light source so that a light beam divergence angle of the display panel is within ±15 degrees.
13 . The air floating video display apparatus according to claim 9 , wherein, in the light source, a part or all of a divergence angle of luminous flux is adjusted by a shape and a surface roughness of the reflection surface of the light source so that a horizontal divergence angle and a vertical divergence angle of a light beam divergence angle of the display panel are different from each other.
14 . The air floating video display apparatus according to claim 9 , wherein the light source has a contrast performance provided by multiplying a resultant contrast based on property of a polarization plate arranged on a light entering surface and a light emitting surface of the video source by inverse of an efficiency of polarization conversion in the polarization converter.
15 . The air floating video display apparatus according to claim 9 , comprising: a reflection-type light polarizer; and the waveplate arranged on a video-light entering surface of the retroreflection optical member, wherein the reflection-type light polarizer is arranged so that the video light emitted from the video source is once reflected by the reflection-type light polarizer and enters the retroreflection optical member, and polarization wave of the video light is converted to another polarization wave when being transmitted twice through the waveplate, and thus, the converted video light is transmitted through the reflection-type light polarizer.
16 . The air floating video display apparatus according to claim 15 , wherein the light source has a contrast performance provided by multiplying a resultant contrast based on properties of two polarization plates arranged on a light entering surface and a light emitting surface of the video source by inverse of an efficiency of polarization conversion in the polarization converter and inverse of a cross transmittance of the reflection-type light polarizer.
17 . An air floating video display apparatus forming an air floating video comprising: an opening portion configured to transmit video light of a specific polarization wave forming the air floating video therethrough; a transparent member arranged at the opening portion and configured to transmit the video light therethrough; a display panel serving as a video source; a light source configured to supply light having specific polarization directionality to the video source; a retroreflection optical member having a retroreflection surface provided with a waveplate; a plurality of reflection mirrors; and a polarization splitter arranged in a space connecting the video source and the retroreflection optical member, wherein the video light of the specific polarization wave emitted from the video source is once transmitted through the polarization splitter, the video light transmitted through the polarization splitter is reflected by a first reflection mirror of the reflection mirrors toward the retroreflection optical member, the video light reflected by the first reflection mirror is converted in terms of light polarization by the retroreflection optical member to convert one polarization wave to another polarization wave, the converted video light is reflected again by the first reflection mirror, the video light reflected again by the first reflection mirror is reflected by the polarization splitter toward the opening portion, the air floating video that is an actual image based on the video light reflected by the polarization splitter is displayed outside the transparent member of the opening portion, the apparatus includes a light block member configured to prevent video light having a divergence angle exceeding a specific angle emitted from the video source from entering the retroreflection optical member, a forming position of the air floating video is changed by a structure changing a distance from the video source to the retroreflection optical member, a surface roughness of a reflection surface of the retroreflection optical member is set so that a ratio of a blur amount of the air floating video to a pixel size of the video source is 40% or less, the light source includes: a point-type or surface-type light source; an optical member configured to reduce a divergence angle of light emitted from the light source; a polarization converter configured to unify the light emitted from the light source to be polarization light having specific directionality; and a light guiding body having a reflection surface configured to propagate light to the video source, the apparatus includes a reflection-type light polarizer, the light guiding body faces the video source, its inside or its surface has a reflection surface configured to reflect the light emitted from the light source toward the video source, and performs polarization conversion to convert light having specific polarization directionality reflected by the reflection-type light polarizer to a polarization wave allowed to be transmitted through the reflection-type light polarizer by transmitting the light through a surface connecting the adjacent reflection surfaces of the light guiding body, reflecting the light at a reflection plate arranged on a surface of the light guiding body opposite to a surface in contact with the video source, and transmitting the light twice through a waveplate arranged on an upper surface of the reflection plate, and transmits the converted light through the light guiding body to propagate the converted light toward the video source, the video source modulates light intensity in accordance with a video signal, in the light source, a part or all of a divergence angle of luminous flux emitted from the light source and entering the video source is adjusted by a shape and a surface roughness of the reflection surface arranged in the light source, and video luminous flux having a narrow divergence angle emitted from the video source is reflected by the retroreflection optical member to aerially form the air floating video.
18 . The air floating video display apparatus according to claim 17 , wherein, in the light source, a part or all of the divergence angle of the luminous flux is adjusted by a shape and a surface roughness of the reflection surface arranged in the light source, so that a light beam divergence angle of the display panel is within ±30 degrees.
19 . The air floating video display apparatus according to claim 17 , wherein, in the light source, a part or all of a divergence angle of luminous flux is adjusted by the shape and surface roughness of the reflection surface of the light source, so that a light beam divergence angle of the display panel is within ±10 degrees.
20 . The air floating video display apparatus according to claim 17 , wherein, in the light source, a part or all of a divergence angle of luminous flux is adjusted by the shape and surface roughness of the reflection surface of the light source, so that a horizontal divergence angle and a vertical divergence angle of a light beam divergence angle of the display panel are different from each other.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is based on PCT filing PCT/JP2021/044151, filed Dec. 1, 2021, which claims priority to JP 2020-217259, filed Dec. 25, 2020, the entire contents of each are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a technique for an air floating video display apparatus for displaying an air floating video to a driver of an automobile, a train, an aircraft, or the like (also referred to as a “vehicle”), and relates to a technique for an air floating video display apparatus using an optical system enabling the driver to view an image of the air floating video as an actual image. BACKGROUND ART A so-called head-up display (HUD) apparatus is known as a video display apparatus configured to project video light onto a windshield or a combiner of a vehicle to form a virtual video to display, for example, traffic information such as automobile route information or traffic jam information, and/or automobile information such as fuel level or coolant temperature. Japanese Patent Application Laid-open Publication No. 2015-194707 (Patent Document 1) discloses an example of the HUD apparatus. RELATED ART DOCUMENTS Patent Documents Patent Document 1: Japanese Patent Application Laid-open Publication No. 2015-194707Patent Document 2: Japanese Patent No. 4788882 SUMMARY OF THE INVENTION Problems to be Solved by the Invention A video display apparatus of this type has been desired to expand a region in which the driver can view a virtual video, while high visual recognition and high resolution of the virtual video are also important performance factors. In addition, some HUDs can perform augmented reality (AR) display where the virtual video is overlaid on the actual image visually recognized by the driver while setting a virtual video producing position more distant from a line of sight of a driver in order to reduce driver's line-of-sight movement. Such an HUD involves a problem where the apparatus or system set is increased in size in order to set the virtual video generating position distant and to achieve high magnification. Furthermore, the above-described HUD apparatus provides the video displayed on the video display apparatus such as a liquid crystal display as the magnified video of the virtual video to the driver by using an optical system including a concave mirror (having a function of a convex lens). As shown in FIG. 2, the windshield 6 of the automobile has a curvature radius “Rv” in a vertical direction of a body and a curvature radius “Rh” in a horizontal direction of the body that are different from each other, and a relation of “Rh>Rv” is generally established. Therefore, as shown in FIG. 22, in the related-art HUD, when the windshield 6 is regarded as the reflection surface, the reflection surface becomes a toroidal surface of the concave mirror 401. Therefore, in the related-art HUD, the shape of the concave mirror 401 is designed to correct the virtual video magnification based on the shape of the windshield 6. In other words, the shape of the concave mirror 401 have an average curvature radius that is different between the horizontal direction and the vertical direction so as to correct the difference between the curvature radius Rv in the vertical direction and the curvature radius Rh in the horizontal direction of the windshield 6. As described above, since the windshield is used as a final reflection surface, a vehicle such as an automobile which assigns importance to designability involves the following problems. Specifically, (1) the design may change until just before mass production, which makes it difficult to finalize design specification, and (2) automobiles have different designs from one another, which makes it difficult to apply an HUD apparatus having the same specification to other automobile models. This application difficulty has hindered HUD market growth. In addition, external light such as sunlight entering the HUD apparatus at a certain angle through the windshield may be collected by the concave mirror 401 and enter a liquid crystal display panel 404. In that case, in order to prevent damage on an emission-side polarization plate of the liquid crystal display panel 404, it is necessary to take a countermeasure such as optimization of a reflection property of the concave mirror 401, and/or arrangement of an optical element 403 configured to reflect a specific polarization wave. An objective of the present invention is to provide a suitable air floating video display apparatus in view of the above-described problems. Means for Solving the Problems In order to solve the above-described problems, for example, configurations recited in claims are employed. An air floating video display apparatus according to an embodiment is an air floating video display apparatus forming an air floating video, and includes: an opening portion configured to transmit video light of a specific polarization wave formi