Patent Description:
Aerial imaging using retro-reflection (AIRR) is known (for example, <CIT>, <CIT>, <CIT>, and <CIT>). Further, <CIT> discloses a display device capable of moving a beam-splitter and a display and satisfactorily observing a planar image of an aerial image.

In a case where an AIRR display device is a desk type, a movable aerial image (or aerial picture) is important as a function thereof. By moving the aerial image, it can be expected that a viewing angle at which a user can observe the aerial image is widened, and a physical limitation of the user is greatly improved. The display device of <CIT> controls the aerial image by moving the beam-splitter and the display, but there are no measures against a display main body entering a field of view during observation of the aerial image.

When the aerial image and the display overlap, a picture of the display enters the aerial image, and a floating feeling of the picture, which is a characteristic of the aerial image, is impaired. <FIG> is a schematic cross-sectional view illustrating a configuration of a conventional desk-type display device. A display device <NUM> includes a display (light source) <NUM> having a screen capable of displaying an image, a beam-splitter <NUM>, a retro-reflective member <NUM>, and a table <NUM> made of transparent glass or the like installed in a housing.

A part of light emitted from the display <NUM> is reflected by the beam-splitter <NUM>, reflected light of the light is incident on the concave retro-reflective member <NUM>, incident light of the reflected light is reflected by the retro-reflective member <NUM> in the same direction as the incident light, and a part of reflected light of the incident light is transmitted through the beam-splitter <NUM> and the table <NUM> and reimaged, so that the aerial image <NUM> is displayed. The aerial image <NUM> is generated at a position symmetrical to the display <NUM> with respect to the surface of the beam-splitter <NUM>. The aerial image <NUM> that can be observed by a user is limited to a range in which the retro-reflective member <NUM> can be viewed from a viewpoint U of the user via the beam-splitter <NUM>.

As illustrated in the drawing, when the display <NUM> enters the field of view from a viewpoint U of the user, the user observes the aerial image <NUM> and an image <NUM> of the display <NUM> in an overlapping manner, and the floating feeling of the aerial image <NUM> is impaired.

<CIT> discloses an aerial display device for displaying an aerial image of an image, which includes a half mirror that emits reflectance and transmitted beam by reflecting and transmit a beam of emitted from the image, a retroreflection sheet that retro-reflects the reflectance or transmitted beam, and a convex lens which is positioned on a light path from the image to the aerial image to expand the size of the aerial image.

An object of the present invention is to provide a display device having a function of preventing an image of a display from entering an aerial image.

The invention relates to a display device according to the appended claims. Embodiments are disclosed in the dependent claims.

A display device according to an aspect of the present invention is capable of displaying an aerial image using retro-reflection, and includes a display capable of displaying an image; a beam-splitter configured to reflect light emitted from the display; a retro-reflective member configured to reflect the light from the beam-splitter in a same direction as incident light; a first variable unit configured to vary an inclination angle of the display; and a second variable unit configured to vary an inclination angle of the beam-splitter.

In an embodiment, the first variable unit includes a mechanism that interlocks with the second variable unit.

According to the present invention, since the beam-splitter and the display are made movable, a movable range of the aerial image can be expanded, whereby the aerial image having a floating feeling can be observed from eye points of various users. In particular, by moving the beam-splitter having high angle dependence of the aerial image, it is possible to expand the movable range of the aerial image while suppressing movement of the display.

A display device of embodiments of the present invention displays an aerial image or an aerial picture using retro-reflection in a three-dimensional space without wearing special glasses or the like. The drawings to be referred to in the description of the following embodiments include exaggerated display in order to facilitate understanding of the invention, and do not directly represent the shape and scale of an actual product.

Next, embodiments of the present invention will be described in detail below. <FIG> is a schematic cross-sectional view illustrating a configuration of the display device according to an embodiment of the present invention. A display device <NUM> of the present embodiment includes a display <NUM> as a light source, a beam-splitter <NUM>, a retro-reflective member <NUM>, and a table <NUM> disposed on the top of a housing (casing) constituting a desk. The display device <NUM> of the present embodiment can move the beam-splitter <NUM> and the display <NUM>, thereby changing a position or an angle at which an aerial image <NUM> is displayed.

The display <NUM> includes a screen <NUM> for displaying an image or a picture, and emits light from the screen <NUM> at a constant emission angle or radiation angle. The display <NUM> is not particularly limited, and for example, a liquid crystal display, an organic EL display, a projection projector, a light emitting diode, a laser diode, or the like can be used.

The display <NUM> is rotatable about an end of the display as a fulcrum such that an inclination angle of the screen <NUM> changes with respect to a reference plane P of the housing. The reference plane P is, for example, a vertical plane. A mechanism for changing the inclination angle of the display <NUM> is not particularly limited, but for example, the display <NUM> may be rotated by a motor or may be rotated using a link mechanism or the like. Here, an angle formed by the reference plane P and a principal plane (screen <NUM>) of the display <NUM> is denoted by ΔDisplay.

The table <NUM> is disposed on, for example, the top of the desk-type housing. The table <NUM> is a transparent plate-like member made of glass, plastic, or the like, and is fixed such that a principal plane of the table is located at approximately <NUM> degrees with respect to the reference plane P.

The beam-splitter <NUM> is disposed below the table <NUM>. The beam-splitter <NUM> is a translucent optical member that separates incident light into reflected light and transmitted light, and reflects a part of light emitted from the screen <NUM> of the display <NUM> toward the retro-reflective member. Note that the beam-splitter <NUM> may be a half mirror in which an amount of the reflected light is equal to an amount of the transmitted light.

The beam-splitter <NUM> is rotatable about an end of the beam-splitter as a fulcrum such that an inclination angle of a principal plane changes with respect to the reference plane P. A mechanism for changing an inclination angle of the beam-splitter <NUM> is not particularly limited, but for example, the beam-splitter <NUM> may be rotated by a motor or may be rotated using a link mechanism or the like. Here, an angle formed by the principal plane of the table <NUM> and the principal plane of the beam-splitter <NUM> is denoted by ΔBS.

The retro-reflective member <NUM> is disposed below the display <NUM>. The retro-reflective member <NUM> is an optical member that reflects light in the same direction as the incident light, and the configuration thereof is not particularly limited but is configured by, for example, a prismatic retro-reflective element such as a triangular pyramid retro-reflective element or a full cube corner retro-reflective element, or a bead retro-reflective element. The retro-reflective member <NUM> is configured as, for example, a concave mirror, and reflects light incident from the beam-splitter <NUM> toward the beam-splitter <NUM>.

The aerial image <NUM> is generated at a position symmetrical to the display <NUM> with respect to the principal plane of the beam-splitter <NUM>. Here, an angle formed by a principal plane of the aerial image <NUM> and the reference plane P is denoted by ΔAerial, and an angle formed by the principal plane of the aerial image <NUM> and the principal plane of the display <NUM> is denoted by Δθ.

The aerial image <NUM> that can be observed by a user is limited to a range in which the retro-reflective member <NUM> can be viewed from the viewpoint U of the user via the beam-splitter <NUM>. Further, the optimum angle or direction for the user to observe the aerial image <NUM> is a direction in which the aerial image <NUM> is viewed from directly above, that is, a direction perpendicular to the principal plane of the aerial image <NUM>. When the display <NUM> enters the field of view viewed from this direction of the viewpoint, the image or picture of the display <NUM> enters the aerial image <NUM>, and the floating feeling of the aerial image <NUM> is lost.

In the present embodiment, to prevent the display <NUM> from entering the field of view of the user, an angle Δθ formed by the aerial image <NUM> and the display <NUM> is set to <NUM> degrees or more.

The relationship at this time is shown in mathematical expression (<NUM>).

When Δθ is <NUM> degrees or more, the user cannot view the image on the screen <NUM> of the display <NUM>.

ΔDisplay is minimized to satisfy the mathematical expression (<NUM>). Since the purpose is to expand a movable range of ΔAerial, it is effective to move the beam-splitter <NUM>. The relationship among ΔAerial, ΔBS, and ΔDisplay when the beam-splitter <NUM> is moved is shown in mathematical expression (<NUM>).

As shown in the mathematical expression (<NUM>), the movement of the beam-splitter <NUM> can make the movement of the aerial image <NUM> larger than the movement of the display <NUM> does, and the movement of the ΔDisplay can be suppressed by ΔBS × <NUM>. By moving the beam-splitter <NUM>, it is possible to expand the movable range of the aerial image <NUM> and implement the mathematical expression (<NUM>) while minimizing the movement of the display <NUM>. Suppressing the movement of the display <NUM> also leads to space saving of the housing.

<FIG> illustrate movable ranges of the aerial image <NUM> when the display <NUM> and the beam-splitter <NUM> are moved. <FIG> illustrate the aerial image <NUM> when the beam-splitter <NUM> is moved in a state where an inclination angle of the display is made relatively small. In this case, Δθ is <NUM> degrees or more, and the aerial image <NUM> is appropriately movable. <FIG> illustrate the aerial image <NUM> when the beam-splitter <NUM> is moved in a state where the inclination angle of the display is made larger than that in <FIG>. The aerial image <NUM> is considerably inclined toward the table <NUM>, and Δθ is less than <NUM> degrees. In this case, the aerial image <NUM> is excessively movable.

<FIG> illustrates an example of an angle adjustment mechanism of the present embodiment. An angle adjustment mechanism <NUM> includes an extensible link <NUM> that connects the display <NUM> and the beam-splitter <NUM>. One end of the link <NUM> is rotatably and slidably connected in a groove formed along a side of the display <NUM>, and the other end is rotatably and slidably connected in a groove formed along a side of the beam-splitter <NUM>. The angle adjustment mechanism <NUM> rotates both the display <NUM> and the beam-splitter <NUM> in conjunction with each other so as to satisfy the relationship shown in the mathematical expression (<NUM>), adjusts ΔBS and ΔDisplay, and moves the aerial image <NUM>.

As an example, a movable range (ΔAerial) of the aerial image <NUM> is assumed to be <NUM>° to <NUM>° as illustrated in the table of <FIG>. This table illustrates the relationship between the inclination angle (ΔBS) of the beam-splitter <NUM> and the inclination angle (ΔDisplay) of the display <NUM> when ΔAerial is set according to the mathematical expression (<NUM>). Further, <FIG> illustrate examples in which ΔAerial = <NUM>°, ΔAerial = <NUM>°, ΔAerial = <NUM>°, and ΔAerial = <NUM>° are set according to ΔBS and ΔDisplay defined in the table. For example, when ΔAerial is set to <NUM>°, ΔBS = <NUM>° and ΔDisplay = <NUM>° are adjusted.

In these examples, when ΔAerial = <NUM>° illustrated in <FIG>, the condition of Δθ ≥ <NUM>° defined in the mathematical expression (<NUM>) is satisfied. That is, <MAT>.

The inclination angles of ΔBS and ΔDisplay defined in the table of <FIG> are merely examples, and other inclination angles may be used. For example, when ΔAerial is set to <NUM>°, ΔBS = <NUM>° and ΔDisplay = <NUM>° may be set according to the mathematical expression (<NUM>), and when ΔAerial is set to <NUM>°, ΔBS = <NUM>° and ΔDisplay = <NUM>° may be set. Further, in the above embodiment, an example in which the angle adjustment mechanism <NUM> interlocks the beam-splitter <NUM> and the display <NUM> has been described but this is an example, and the angle adjustment mechanism <NUM> may separately rotate or move the beam-splitter <NUM> and the display <NUM> by independent mechanisms.

Next, another embodiment of the present embodiment will be described. <FIG> is a block diagram illustrating a configuration of a display device of the present embodiment. A display device <NUM> includes an input unit <NUM> that receives an input from the user, an imaging unit <NUM>, a seat information acquisition unit <NUM>, a storage unit <NUM>, a display unit <NUM>, a beam-splitter drive unit <NUM>, a display drive unit <NUM>, a sound output unit <NUM>, and a control unit <NUM>.

The display device <NUM> of the present embodiment is mounted on a vehicle, for example. The imaging unit <NUM> captures a space inside the vehicle and provides captured image data to the control unit <NUM>. The seat information acquisition unit <NUM> acquires information regarding the vehicle. Seat information includes, for example, a seat position of a seat, an inclination angle of a backrest, and the like. The storage unit <NUM> stores various data, application software, and the like necessary for the display device <NUM>. For example, image data to be displayed on the display <NUM>, sound data output from the sound output unit <NUM>, and the like are stored.

The display unit <NUM> includes the display <NUM>, the beam-splitter <NUM>, the retro-reflective member <NUM>, the table <NUM>, and the like as illustrated in <FIG>. The beam-splitter drive unit <NUM> varies the inclination angle of the beam-splitter <NUM>. For example, the beam-splitter drive unit <NUM> drives a motor connected to the beam-splitter <NUM> to vary the inclination angle of the beam-splitter <NUM>. The display drive unit <NUM> varies the inclination angle of the display <NUM>. For example, the display drive unit <NUM> drives a motor connected to the display to vary the inclination angle of the display. The sound output unit <NUM> outputs, for example, sound corresponding to an image displayed by the display unit <NUM>. The control unit <NUM> controls the image displayed by the display unit <NUM> and controls the beam-splitter drive unit <NUM> and the display drive unit <NUM>.

In a certain mode, the control unit <NUM> estimates an optimum angle of the aerial image when observed from the viewpoint of the user, and controls the beam-splitter drive unit <NUM> and the display drive unit <NUM> on the basis of the estimated optimum angle to implement Δθ ≥ <NUM>°.

To estimate the optimum angle of the aerial image, the control unit <NUM> analyzes the image data captured by the imaging unit <NUM> and calculates the viewpoint (three-dimensional coordinate position) of the user. The viewpoint (eye point) is a center position of left and right eyes. Further, an initially set mounting position (height, angle (ΔDisplay), and the like) of the display <NUM> and a mounting position of the beam-splitter <NUM> are known. In view of the configuration that the aerial image <NUM> is generated at the position symmetrical with respect to the principal plane of the beam-splitter, the control unit <NUM> estimates the optimum angle (ΔAerial) of the aerial image <NUM> for viewing the aerial image <NUM> in a vertical direction from the calculated viewpoint. Then, the angles at which the beam-splitter <NUM> and the display <NUM> are rotated are calculated on the basis of the estimated optimum angle so as to satisfy the mathematical expressions (<NUM>) and (<NUM>), and the beam-splitter drive unit <NUM> and the display drive unit <NUM> are controlled according to the calculated angles.

For example, when <NUM>° is estimated as the optimum angle (ΔAerial) of the aerial image, the control unit <NUM> calculates ΔBS = <NUM>° and ΔDisplay = <NUM>° from the mathematical expression (<NUM>) or the table of <FIG>, and controls the driving of the beam-splitter drive unit <NUM> and the display drive unit <NUM> on the basis of the calculated values.

Further, as another method of calculating the viewpoint of the user, the control unit <NUM> may calculate the viewpoint of the user using the seat information acquired from the seat information acquisition unit <NUM> and standard body information (for example, a sitting height, a height of the head when the user sits on a seat, and the like) prepared in advance in the storage unit <NUM>.

As described above, according to the present embodiment, the viewpoint of the user is calculated, the optimum angle (ΔAerial) of the aerial image is estimated from the calculated viewpoint, and the angles at which the beam-splitter <NUM> and the display <NUM> are rotated are calculated on the basis of the estimated optimum angle, whereby the user can automatically adjust ΔBS and ΔDisplay without any operation. As a result, the user can observe the aerial image having a floating feeling.

In the above embodiment, ΔBS and ΔDisplay are automatically adjusted. However, in an embodiment not according to the claimed invention, the user may input an instruction for adjusting ΔBS or the ΔDisplay from the input unit <NUM>.

In the above embodiment, an example in which the aerial image <NUM> is generated using the beam-splitter <NUM> and the retro-reflective member <NUM> has been described. However, a polarization beam-splitter may be used instead of the beam-splitter <NUM>, and a λ/<NUM> plate may be arranged on the upper surface side of the retro-reflective member <NUM>. The polarization beam-splitter reflects light from the display <NUM>, and the λ/<NUM> plate allows the light reflected by the polarization beam-splitter to enter the plate and transmits the incident light with a phase difference π/<NUM> (<NUM> degrees). The retro-reflective member <NUM> reflects the light transmitted through the λ/<NUM> plate in the same direction as the incident light. When the light reflected by the retro-reflective member <NUM> is transmitted through the λ/<NUM> plate again, the phase difference π/<NUM> is provided. Thus, the light transmitted through the λ/<NUM> plate has a phase difference π from the light incident on the λ/<NUM> plate. For example, in a case where the light incident on the λ/<NUM> plate is linearly polarized light, the light becomes circularly polarized light (or elliptically polarized light) when passing through the λ/<NUM> plate, when the circularly polarized light is retro-reflected an odd number of times by the retro-reflective member <NUM>, the circularly polarized light becomes circularly polarized light in an opposite direction, and when this circularly polarized light in the opposite direction passes through the λ/<NUM> plate, the circularly polarized light becomes linearly polarized light in a direction <NUM> degrees different from the original linearly polarized light. In this way, when the light transmitted through the λ/<NUM> plate is incident on the polarization beam-splitter, most of the light is transmitted through the polarization beam-splitter, the transmitted light forms an image, and the aerial image is formed.

Next, a specific demonstration example in the display device of the present embodiment will be described. A target height of an observer is <NUM> to <NUM>. <NUM> is an average height of elementary school students, and <NUM> covers the heights of most adults. <FIG> illustrates an average sitting height of the adult and the elementary school student. Further, the eye point (viewpoint) is denoted by the eye point = the sitting height -<NUM>. <FIG> illustrates eye points of the adult and the elementary school student.

Next, a method of calculating optimum values of a desk and a chair based on ergonomics is as follows. <MAT> <MAT>.

For example, the average height of Japanese adults is about <NUM>. In this case, the seat height of the chair is <NUM>, and the height of the desk is <NUM>.

<FIG> is a diagram illustrating a calculation example of the optimum angle (ΔAerial) of the aerial image from the eye point. The optimum angle of the aerial image is calculated by the following equation, where the sitting height of the average adult is <NUM>, the seat height of the chair is <NUM>, the height of the eye point from a ground contact surface of the chair is <NUM>, the height of the desk is <NUM>, and a minimum required distance between the desk and the observer is <NUM>, as illustrated in the drawing.

According to this mathematical expression, ΔAerial is <NUM> degrees when the height of the eye point is <NUM>.

Incidentally, ΔAerial is <NUM> degrees in the case where the height of the eye point is <NUM> that is the maximum value, and ΔAerial is <NUM> degrees in the case where the height of the eye point is <NUM> that is the minimum value.

In the case where the optimum angle of the aerial image is ΔAerial = <NUM>°, Δθ = <NUM>° - (<NUM>° + <NUM>°) = <NUM>° in the mathematical expression (<NUM>), and Δθ < <NUM>° is obtained. Here, the beam-splitter <NUM> is horizontal (ΔBS = <NUM>°) and the ΔDisplay of the display <NUM>, which is symmetrical with respect to the principal plane of the beam-splitter <NUM>, is <NUM>°. In this state, the picture of the display <NUM> enters the field of view of the user.

Therefore, in the present embodiment, the table of <FIG> is referred to and ΔAerial = <NUM> closest to the optimum angle is referred to, and the angle of the beam-splitter <NUM> is adjusted to ΔBS = <NUM>° and the angle of the display <NUM> is adjusted to ΔDisplay = <NUM>°. As a result, Δθ = <NUM>° - (<NUM>° + <NUM>°) ≈ <NUM>° of the mathematical expression (<NUM>) is obtained, and Δθ > <NUM>° can be obtained.

<FIG> is a diagram illustrating a calculation example of the optimum angle (ΔAerial) of the aerial image when the backrest of the seat is inclined. As illustrated in the drawing, the optimum angle of the aerial image is calculated by the following equation, where the sitting height of the average adult is <NUM>, the seat height of the chair is <NUM>, the inclination angle of the backrest is <NUM>°, the desk height is <NUM>, and the minimum required distance between the desk and the observer is <NUM>.

In the case where the backrest is inclined, the optimum angle of the aerial image becomes small, and thus, as the movable range of the aerial image, a range from <NUM>° to <NUM>° is required as illustrated in <FIG>. In this case, the picture of the display <NUM> does not enter the field of view of the user even if the beam-splitter <NUM> is not moved.

As described above, according to the display device of the present embodiment, by moving the beam-splitter <NUM> having high angle dependency of ΔAerial, the movable range of the aerial image can be expanded as compared with a case where only the display is movable. Further, space saving of the housing can be expected by minimizing the movement of the display. Further, for children to adults with different eye points or users with different physical characteristics, it is possible to observe the aerial image with a floating feeling that the picture of the display does not enter.

Claim 1:
A display device (<NUM>) capable of displaying an aerial image (<NUM>) using retro-reflection, the display device (<NUM>) comprising:
a display (<NUM>) capable of displaying an image;
a beam-splitter (<NUM>) configured to reflect light emitted from the display (<NUM>);
a retro-reflective member (<NUM>) configured to reflect the light from the beam-splitter (<NUM>) in a same direction as incident light,
a first variable unit (<NUM>) configured to vary an inclination angle of the display (<NUM>) formed by a reference plane (P) of a housing and a principal plane of the display (<NUM>); and
a second variable unit (<NUM>) configured to vary an inclination angle of the beam-splitter (<NUM>) with respect to the reference plane (P),
the display device (<NUM>) being characterized by
a control unit (<NUM>) configured to calculate a viewpoint of the user, to estimate an optimum angle ΔAerial of the aerial image (<NUM>) when observing the aerial image (<NUM>) on a basis of the calculated viewpoint from a direction perpendicular to a principal plane of the aerial image (<NUM>), wherein ΔAerial is an inclination angle of the aerial image (<NUM>) generated at a position symmetric to the display (<NUM>) with respect to the beam-splitter (<NUM>) formed by the principal plane of the aerial image (<NUM>) and the reference plane (P), and to control the first variable unit (<NUM>) and the second variable unit (<NUM>) on a basis of the estimated optimum angle ΔAerial to satisfy Δθ = <NUM> - (ΔAerial + ΔDisplay) ≥ <NUM> degrees,
where the inclination angle of the display (<NUM>) is denoted by ΔDisplay, and an angle formed by the aerial image (<NUM>) and the display (<NUM>) is denoted by Δθ.