Holographic image display device

A holographic image display device according to one embodiment comprises: an image display unit on which a holographic image is displayed; and a spatial impression providing unit which forms a space surrounding the holographic image, and includes a transparent color material such that the space looks colored and the holographic image can be recognized from the outside.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a national stage filing under 35 U.S.C § 371 of PCT application number PCT/KR2018/012404 filed on Oct. 19, 2018 which is based upon and claims the benefit of priorities to Korean Patent Application No. 10-2017-0136878, filed on Oct. 20, 2017, in the Korean Intellectual Property Office. The disclosures of the above-listed applications are hereby incorporated by reference herein in their entireties.

TECHNICAL FIELD

The present disclosure relates to a holographic image display device.

BACKGROUND

A hologram is a recording of interference patterns of light such as laser light on a recording medium such as a film or a photosensitive dry plate. The hologram provides a stereoscopic image of an object. For example, a hologram of a person's head provides different images depending on the viewing position. That is, the left side of the person's head is seen in a position, the front side of the person's head is seen in another position and the right side of the person's head is seen in still another position.

Meanwhile, a pseudo hologram refers to a technique that produces a hologram-like effect, although it is not the hologram itself. In the pseudo hologram, a half-mirror film type screen or a transmissive screen may be employed.

However, when the half-mirror film type screen is employed, the screen should be arranged to be inclined at an angle of about 45 degrees. In this case, the volume of such a holographic image display device is increased compared to the volume of a holographic image display device that does not employ the half-mirror film type screen.

In addition, the degree of freedom of configuration in which the half-mirror film type screen is employed is lower than that of the holographic image display device which does not employ the half-mirror film type screen. Meanwhile, when employing a transmissive screen, the screen should be transparent. In this case, when the ambient illumination is high, the holographic image is not seen clearly.

SUMMARY

In view of the above, the present disclosure provides a holographic image display device capable of clearly providing a pseudo holographic image.

It is to be understood, however, that the object of the present disclosure is not limited to those mentioned above. Other objects not mentioned above will be clearly understood by those skilled in the art from the following description.

In accordance with an aspect of the present disclosure, there is provided a holographic image display device comprising: an image display unit configured to display a holographic image; and a spatial impression providing unit configured to form a space surrounding the holographic image, the spatial impression providing unit comprising a colored transparent material which allows the holographic image to be seen through the spatial impression providing unit from outside while allowing the space to be seen colored.

In accordance with the embodiment of the present disclosure, since the background of the holographic image can be seen colored, the observer can clearly recognize the holographic image even when the ambient illumination is bright.

Further, the ghost phenomenon can be reduced or eliminated.

In addition, it is possible to provide a holographic image with a wider viewing angle than that in the conventional case.

DETAILED DESCRIPTION

The advantages and features of the embodiments and the methods of accomplishing the embodiments will be clearly understood from the following description taken in conjunction with the accompanying drawings. However, embodiments are not limited to those embodiments described, as embodiments may be implemented in various forms. It should be noted that the present embodiments are provided to make a full disclosure and also to allow those skilled in the art to know the full range of the embodiments. Therefore, the embodiments are to be defined only by the scope of the appended claims.

In describing the embodiments of the present disclosure, if it is determined that detailed description of related known components or functions unnecessarily obscures the gist of the present disclosure, the detailed description thereof will be omitted. Further, the terminologies to be described below are defined in consideration of the functions of the embodiments of the present disclosure and may vary depending on a user's or an operator's intention or practice. Accordingly, the definition thereof may be made on a basis of the content throughout the specification.

FIG. 1is a perspective view of art appearance of a holographic image display device according to one embodiment. However, sinceFIG. 1is merely an example, the present disclosure is not limited to the holographic image display device illustrated inFIG. 1. In addition, the 3D coordinate axes (x, y, and z axes) shown inFIG. 1are associated with the 2D coordinate axes shown inFIGS. 4to12.

The holographic image display device100may be a device that provides a pseudo hologram. Thus, the image10shown inFIG. 1and the image10to be described below refer to a pseudo holographic image or a holographic image.

Referring toFIG. 1, the holographic image display device100includes a case160forming an appearance thereof and a spatial impression providing unit120.

A power supply unit (not shown) and at least some components of an image display unit for displaying the image10are installed at the case160. The power supply unit serves to supply power to the image display unit, an illuminance sensor unit or a control unit to be described later.

The case160is formed of a transparent or translucent material to allow an observer to see the inside of the case160. Alternatively, the case160may be formed of an opaque material not to allow an observer to see the inside of the case160.

The spatial impression providing unit120forms a space121surrounding the image10. The space121may be formed by only the spatial impression providing unit120or by the spatial impression providing unit120and one end surface of the case160as illustrated inFIG. 1.

The spatial impression providing unit120is formed of a transparent material, and thus an external observer can recognize the image10displayed in the space121through the spatial impression providing unit120. Here, when the image10is displayed in the space121, this may be referred to as “the image is floated.” In this case, the observer can recognize the image10in the form of a holographic image, that is, a stereoscopic image.

Meanwhile, the space121may be recognized as the background of the image10from an observer's point of view. Further, depending on the position of the observer, the space121may be recognized as a background having the same or similar brightness and color as the surroundings. However, if the space121is recognized brightly due to the bright illumination around the holographic image display device100, the image10displayed in the background of the space121may not be clearly seen by the observer.

The present embodiment provides a technology in which the space121recognized as the background of the image10can be seen dark even if the ambient illumination is bright.

Hereinafter, a configuration of the holographic image display device100that provides such a technology will be described in detail.

FIG. 2is a diagram conceptually illustrating a configuration of the holographic image display device illustrated inFIG. 1.FIG. 2merely shows an example of the configuration of the holographic image display device, and the present disclosure is not limited to those shown inFIG. 2.

Referring toFIG. 2, the holographic image display device100includes an image display unit110and a spatial impression providing unit120. In some embodiments, the holographic image display device100may further include at least one of an illuminance sensor unit130, a control unit140, a light scattering unit150, and a case160. Further, the holographic image display device100may further include other components that are not shown in the drawings.

First, the image10is displayed by the image display unit110. As described above, the image10may be a pseudo holographic image referred to in the field of pseudo holograms as described above. The image display unit110includes a configuration for generating an image and a configuration for displaying an image, such as a projector or a liquid crystal panel. The holographic image display devices100implemented by various image display units110will be described in more detail with reference toFIGS. 4 to 12.

The spatial impression providing unit120forms a space121surrounding the image10. The space121may be formed by only the spatial impression providing unit120or by the spatial impression providing unit120and one end surface of the case160.

The spatial impression providing unit120is formed of a transparent material, and thus an external observer can visually recognize the image10displayed in the space121through the spatial impression providing unit120. Here, when the image10is displayed in the space121, this may be referred to as “the image is floated.”

Meanwhile, the expression “the image10is displayed in the space121” means that the space121is recognized as the background of the image10from an observer's point of view. In this case, the illuminance around the holographic image display device100may be reflected in the space121that is visually recognized as the background of the image by the observer. If the illuminance around the holographic image display device100is relatively higher than the brightness of the image10, the observer30may not recognize the image10clearly.

According to one embodiment, the spatial impression providing unit120is formed of a transparent and colored material. Such a colored material includes colored acrylic, polycarbonate (PC), polymethyl methacrylate (PMMA) or the like having low light transmittance in the visible light region, but the present disclosure is not limited thereto. In addition, the light transmittance of the spatial impression providing unit120may be, e.g., 30% or less in the visible light region.

Accordingly, according to the present embodiment, since the space serving as the background of the image can be seen colored, the observer can clearly recognize the image even when the ambient illumination is bright.

Meanwhile, the spatial impression providing unit120comprises an anti-reflection coating member122. The anti-reflective coating member122is applied to at least one of an inner surface (facing the image10) or an outer surface (facing an observer) of the spatial impression providing unit120. The anti-reflection coating member122prevents or suppresses the image10displayed by the image display unit110from being reflected from the inner surface of the spatial impression providing unit120. Therefore, the phenomenon that a ghost image is visible to the observer can be reduced or eliminated. Meanwhile, according to one embodiment, the spatial impression providing unit120comprises a dynamic dye filter123, and the dynamic dye filter123is applied to the inner surface or the outer surface of the spatial impression providing unit120. When the spatial impression providing unit120is implemented by the dynamic dye filter123, the degree of color of the spatial impression providing unit120may vary depending on the illuminance around the pseudo holographic image display device100and therefore the light transmittance may also vary. For example, when the ambient illuminance is increased, the degree of color of the spatial impression providing unit120implemented by the dynamic dye filter123is increased to lower the light transmittance, and vice versa.

The illuminance sensor unit130is disposed on an outer circumferential surface of the holographic image display device100to detect the illuminance around the holographic image display device100. The illuminance sensor unit130may be configured as a sensor for calculating illuminance based on the brightness of light inputted thereto, and since the configuration itself is general, a description thereof will be omitted.

The control unit140receives an ambient illuminance from the illuminance sensor unit130and controls the luminance of the image10displayed by the image display unit110based on the received ambient illuminance. As described above, the spatial impression providing unit120comprises a colored transparent material, which decreases the light transmittance of the spatial impression space providing unit120. In this case, the brightness in the space121is lowered due to the low light transmittance, but the brightness of the image10seen by the observer may also be lowered. Accordingly, the control unit140can control the luminance of the image display unit110to be high or low in consideration of the ambient illuminance to solve this problem. For example, if the ambient illuminance is higher than a predetermined reference value, the luminance of the image display unit110is controlled to be high, whereas if the ambient illuminance is lower than the predetermined reference value, the luminance of the image display unit110is controlled to be low. The control unit140may be implemented by a memory storing instructions programmed to perform such a function, and a microprocessor executing the instructions. In addition, the control unit140may perform various functions in addition to controlling the luminance of the image display unit110.

The light scattering unit150scatters light incident on the image display unit110. The light scattering unit150is disposed on the image display unit110, and may be formed to include, e.g., acrylic beads or the like or may be formed by etching the surface thereof. The scattering angle of the light can be adjusted by the light scattering unit150to adjust the viewing angle of the image10.

The case160forms an outer appearance of the holographic image display device100. Since the case160has already been described with reference toFIG. 1, a detailed description thereof will be omitted.

As described above, according to one embodiment, since the space serving as the background of the image can be seen colored, the observer can clearly recognize the image even when the ambient illumination is bright. Further, the ghost phenomenon can be reduced or eliminated. In addition, it is possible to provide a pseudo holographic image with a wider viewing angle than in the conventional case.

Hereinafter, various embodiments of the holographic image display device will be described.

First, the image display unit110may be implemented in the form of a projector or a liquid crystal panel.FIGS. 3 to 9illustrate cases where the image display unit110is implemented in the form of a projector, andFIG. 10illustrates a case where the image display unit110is implemented in the form of a liquid crystal panel. The cases where the image display unit110is implemented in the form of a projector will be described first with reference toFIGS. 3 to 9.

FIG. 3is a diagram illustrating a configuration in which the image display unit110illustrated inFIG. 2is implemented in the form of a projector. When the image display unit110is implemented in the form of a projector, the projector may be an ultra-short throw (UST) projector, but is not limited thereto.

Referring toFIG. 3, the image display unit110includes an image projector111, a mirror unit112, and a screen unit113. The image projector111generates and projects the image10, and includes RGB light sources as components. Since the image projector111itself is well known in the projector field, a detailed description thereof will be omitted.

The mirror unit112is configured to reflect the image10incident from the image projector111toward the screen unit113to be described later. The reflection angle of the mirror unit112can be controlled by the control unit140. The mirror unit112may be implemented in the form of a mirror. Since the mirror unit112itself is well known in the field of projection projectors, a detailed description thereof will be omitted.

An image10is formed on the screen113. The image10formed on the screen unit113may be an image10reflected from the mirror unit112. The screen unit113may be a reflective type or a transmissive type, and may be formed of a transparent or semitransparent material. When the image10is input to the reflective screen113, the image10is reflected toward the observer. On the other hand, when the image10is input to the transmissive screen113, the image10is irradiated toward the observer after passing through the transmissive screen113.

FIG. 4is a side cross-sectional view of an image display unit110employing a reflective type screen unit113and a holographic image display device100including such an image display unit110.

Referring toFIG. 4, the holographic image display device100includes an image display unit110, a spatial impression providing unit120, and a case160. The image display unit110includes an image projector111, a mirror unit112, and a screen unit113. The image projector111and the mirror unit112are disposed in a lower portion of the holographic image display device100.

The image10projected from the image projector111is reflected by the mirror112. The image10reflected by the mirror unit112reaches the reflective type screen unit113and is reflected by the screen unit113to be directed toward the observer30.

The reflective type screen unit113illustrated inFIG. 4includes a first surface and a second surface. The first surface is a surface which reflects the image10, and the second surface is a surface to which light introduced from the outside is irradiated. This will be described in detail with reference toFIG. 5.

FIG. 5an enlarged cross-sectional view of the reflective type screen unit113inFIG. 4. However, the cross section of the screen unit113shown inFIG. 5is illustrative purpose only.

Referring toFIG. 5, the reflective type screen unit113includes first surfaces113aand second surfaces113b. As illustrated, the first surfaces113aand the second surfaces113bare alternately formed on the screen unit113. In addition, the first surface113aand the second surface113bare formed at a predetermined angle with each other.

The first surface113areflects the input image10reflected from the mirror unit112toward the observer30. The first surface113amay be one surface of a Fresnel lens or one surface of a prism array.

The second surface113bis a surface on which an absorbing member for absorbing light introduced from external lighting20, e.g., sunlight or artificial lighting, is disposed. Any kind of material may be employed as the absorbing member as long as the material can absorb light. When the light from the outside is absorbed by the second surface113b, the brightness of the space121becomes lower, and thus the image10can be more clearly seen by the observer30.

Meanwhile, as shown inFIG. 5, the light scattering unit150is disposed on the screen unit113. The light scattering unit150is configured to scatter light. The light scattering unit150may be formed to have, e.g., acrylic beads or may be formed by etching the surface thereof. The scattering angle of the light can be adjusted by the light scattering unit150to adjust the viewing angle of the image10.

FIG. 6is a side cross-sectional view of the holographic image display device100in a case where the image projector111and the mirror portion112are disposed in an upper portion of the holographic image display device100unlikeFIG. 4. Here, since the other configurations of the holographic image display device100except for the arrangement of the image projector111and the mirror112are the same as those of the holographic image display device100shown inFIG. 4, a redundant description thereof will be omitted.

FIG. 7is a side cross-sectional view of the holographic image display device100including the image display unit110employing the transmissive type screen unit113, unlikeFIGS. 4 to 6.

Referring toFIG. 7, the holographic image display device100includes an image display unit110, a spatial impression providing unit120, or a case160. The image display unit110includes an image projector111, a mirror unit112, and a screen unit113. The image projector111and the mirror unit112are disposed in a lower portion of the holographic image display device100.

The image10projected from the image projector111is reflected by the mirror112. The image10reflected by the mirror unit112reaches the transmissive type screen unit113and transmits through the screen unit113to be directed toward the observer30. Here, the image10transmitting through the screen unit113passes through the space121to be directed toward the observer30.

FIG. 8is a side cross-sectional view of the holographic image display device100in a case where the image projector111and the mirror portion112are disposed in an upper portion of the holographic image display device100unlikeFIG. 7. Here, since the other configurations of the holographic image display device100except for the arrangement of the image projector111and the mirror112are the same as those of the holographic image display device100shown inFIG. 7, a redundant description thereof will be omitted.

FIG. 9is an enlarged view of a portion “A” in the transmissive screen unit113illustrated inFIG. 7. Referring toFIG. 9, the transmissive screen unit113is formed in the form of a prism113c. When the image10is inputted to the transmissive screen unit113from the mirror unit112, the image10transmits through the transmissive screen unit113in the form of the prism113cto be directed toward the observer30.

Meanwhile,FIG. 10is a side cross-sectional view of the holographic image display device100including an image display unit implemented in the form of a liquid crystal panel, unlikeFIGS. 3 to 9. Referring toFIG. 10, the holographic image display device100includes an image display unit210,211and a spatial impression providing unit120. In some embodiments, the holographic image display device100further includes an illuminance sensor unit, a control unit (not shown), or a case160. The spatial impression providing unit120, the illuminance sensor unit, the control unit or the case160are the same as those shown inFIG. 2, descriptions thereof will be omitted.

The image display unit210,211includes a panel210for displaying a holographic image, and a backlight unit (BLU)211for providing a backlight to the panel210. Here, the backlight unit211may be a direct LED BLU. When using the backlight unit211of the direct LED BLU, it is possible to provide a backlight with a brighter brightness. Therefore, even if the spatial impression providing unit120includes a colored transparent material and has a low light transmittance, the image10can have brightness sufficient to allow the observer30to clearly recognize the image10.

FIGS. 11 and 12are cross-sectional views of the holographic image display device100employing various types of spatial impression providing units120. Referring toFIGS. 11 and 12, the spatial impression providing unit120has a hemispherical shape or a cubic shape, and may be elliptical unlike those shown inFIGS. 11 and 12without being limited thereto.

As shown inFIG. 11, when the spatial impression providing unit120has the hemispherical shape, the image10can be observed in any direction of the spatial impression providing unit120. Therefore, in this case, the image display unit110can determine the luminance of the image10under the premise that the image10can be observed in all directions of the spatial impression providing unit120.

On the other hand, as shown inFIG. 12, when the spatial impression providing unit120has the cubic shape, the image10can be seen through only one surface120aof the spatial impression providing unit120. Therefore, in this case, the image display unit110can determine the luminance of the image10under the premise that the image10can be observed on only one surface120aof the spatial impression providing unit120. When the holographic image display device100shown in each ofFIGS. 11 and 12includes the screen unit113having the same diameter and provides the image10having the same luminance, the power of the image display unit110should be greater inFIG. 11than inFIG. 12. This is because the image10needs to be observed from all sides in the case ofFIG. 11, while the image10needs to be observed only from one side120ain the case of inFIG. 12.

As described above, according to one embodiment, since the space serving as the background of the image can be seen colored, the observer can clearly recognize the image even when the ambient illumination is bright. Further, the ghost phenomenon can be reduced or eliminated. In addition, it is possible to provide a pseudo holographic image with a wider viewing angle than in the conventional case.

The above description illustrates the technical idea of the present disclosure, and it will be understood by those skilled in the art to which this present disclosure belongs that various changes and modifications may be made without departing from the scope of the essential characteristics of the present disclosure. Therefore, the exemplary embodiments disclosed herein are not used to limit the technical idea of the present disclosure, but to explain the present disclosure, and the scope of the technical idea of the present disclosure is not limited by those embodiments. Therefore, the scope of protection of the present disclosure should be construed as defined in the following claims, and all technical ideas that fall within the technical idea of the present disclosure are intended to be embraced by the scope of the claims of the present disclosure.

INDUSTRIAL APPLICABILITY

In accordance with the embodiments of the present disclosure, the holographic image can be more clearly provided to the observer, and the ghost phenomenon can be reduced or eliminated. In addition, it is possible to provide a pseudo holographic image with a wider viewing angle than in the conventional case.