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Patent Issued for Three-Dimensional Holographic Display Using Active Shutter

May 14, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Song, Hoon (Yongin-si, KR); Choi, Yoon-sun (Yongin-si, KR); Lee, Hong-seok (Seongnam-si, KR); Park, Jae-hyeung (Suwon-si, KR), filed on January 18, 2012, was published online on April 29, 2014.

The patent's assignee for patent number 8711455 is Samsung Electronics Co., Ltd. (Suwon-si, KR).

News editors obtained the following quote from the background information supplied by the inventors: "The following description relates to a three-dimensional holographic image display device.

"Three-dimensional image display devices that provide a more realistic and effective display of an image are desired in various fields, such as medical imaging, games, advertisements, education, and the military. Accordingly, as a method of displaying a three-dimensional image, a holographic method and a stereoscopic method have been studied.

"According to a holography method, an interference signal obtained by overlapping a light from an object and a coherent reference light is recorded and reproduced. The holography method provides certain advantages for realizing a three-dimensional image. For example, the holography method has the merit of depth cue, as compared to the stereoscopic method. The stereoscopic method only depends on a binocular depth cue, such as binocular disparity or binocular convergence, but does not provide a monocular depth cue, such as accommodation. A lack of a monocular depth cue may result in disharmony with a depth cue generated by binocular disparity, which may cause visual fatigue of a user. On the other hand, the holography method provides both a binocular depth cue and a monocular depth cue. Accordingly, the holography method may display a three-dimensional image that does not cause substantial visual fatigue, and the holography method may provide a greater sense of a realistic image as compared to the stereoscopic method.

"Despite the advantages of the holography method, there are many restrictions in displaying a three-dimensional image according to the holography method. Examples of such restrictions include an insufficient resolution of a spatial light modulator (SLM), a narrow viewing angle, existence of a direct current (DC) term and a conjugate image, an insufficient diffraction efficiency, a relatively large calculation capacity for a computer-generated hologram, and the like. From among these restrictions, an excessively narrow viewing angle is generally recognized as a main restricting factor. Holography generates a three-dimensional image by recording and reproducing a wavefront pattern. In order to display wavefronts of an object in a relatively wide angle, a pixel having a size corresponding to a size of wavelength is typically required. However, contemporary SLMs cannot make the wavefronts of an object be displayed at a wide angle, and contemporary SLMs only provide a narrow viewing angle to cover a single eye. Accordingly, other methods, such as a method using a plurality of SLMs or a method using a high speed SLM, have been attempted. However, these methods have typically required a complicated optical system and have generally been regarded as uneconomical."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "In one general aspect, there is provided a three-dimensional holographic image display device that includes a spatial light modulator (SLM) to display holograms for a left and a right eye; a light source to irradiate light for reproducing an image onto the SLM; a reproducing lens unit to reproduce an image by converting light emitted from the hologram displayed on the SLM; a beam dividing unit to divide light incident from the reproducing lens unit so as to proceed along a first path and a second path; a right eye active shutter disposed in a light path between the beam dividing unit and the right eye and substantially synchronized with the SLM to transmit or block light; and a left eye active shutter disposed in a light path between the beam dividing unit and the left eye and substantially synchronized with the SLM to transmit or block light.

"The SLM may be a reflective type SLM.

"The SLM may include any one selected from the group of a digital micro-mirror display (DMD), a liquid crystal on silicon (LCoS) display, and a liquid crystal display (LCD).

"The reproducing lens unit may include a first lens to apply a Fourier transform to light reflected by the hologram displayed on the SLM, a mask for substantially removing light that does not correspond to the image to be reproduced from the light that is Fourier-transformed by the first lens; and a second lens for adjusting a magnification and a viewing angle of the image passed through the mask.

"The three-dimensional holographic image display device may further include a first mirror to control a path of light divided by the beam dividing unit that is proceeding along the first path to be directed to the left eye; and a second mirror to control a path of light divided by the beam dividing unit that is proceeding along the second path to be directed to the right eye.

"The holograms for the left and right eye may be computer-generated holograms (CGHs)

"The beam dividing unit may include a half mirror.

"Opening and closing of each of the left and right eye active shutters may be mechanically controlled.

"The left and right eye active shutters may each include an optical device, wherein a light transmittance of the optical device is controlled according to an electric signal.

"The SLM may display the holograms for the left and right eye according to a time division method.

"The three-dimensional holographic image display apparatus may be a head mounted display with a substantially fixed position with respect to each of the left and right eye.

"In another aspect, there is provided a method of displaying a three-dimensional holography image, the method including displaying holograms for a left and a right eye on a spatial light modulator (SLM) according to a time division method; irradiating light for reproducing an image onto the SLM; reproducing an image by converting light emitted from the hologram displayed on the SLM; dividing a path of the converted light into a first path and a second path; and controlling a shutter to regulate transmitting and blocking of light directed to the left and right eye substantially in synchronization with the holograms displayed on the SLM according to the time division method.

"The SLM may be a reflective type SLM.

"The reproducing of the image may include applying a Fourier transform to light reflected by the hologram displayed on the SLM; substantially removing light that does not correspond to the image to be reproduced from the Fourier-transformed light; and adjusting a magnification and a viewing angle of the image.

"The path of the converted light may be divided into the first path and the second path by a half mirror.

"The method may further include adjusting the divided first and second paths to be paths respectively directed to the left and right eye prior to the controlling of the shutter.

"In yet another aspect, there is provided a three-dimensional holographic image display device including a light source; a modulator to display a plurality of holographic images by emitting light irradiated from the light source; a beam splitter to divide the light emitted from the modulator into a plurality of directions; a control unit to transmit data regarding the plurality of holographic images to the modular, to control a left eye active shutter to transmit or block incident light from the beam splitter, and to control a right eye active shutter to transmit or block incident light from the beam splitter.

"When a hologram for a left eye is displayed on the SLM, the left eye active shutter may be controlled to be in an open state to transmit light, and the right eye active shutter may be controlled to be in a closed state to block light.

"When a hologram for a right eye is displayed on the SLM, the left eye active shutter may be controlled to be in an closed state to block light, and the right eye active shutter may be controlled to be in a open state to transmit light.

"The control unit may transmit the data regarding to plurality of holographic images to the modular according to a time division method."

For additional information on this patent, see: Song, Hoon; Choi, Yoon-sun; Lee, Hong-seok; Park, Jae-hyeung. Three-Dimensional Holographic Display Using Active Shutter. U.S. Patent Number 8711455, filed January 18, 2012, and published online on April 29, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=56&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2770&f=G&l=50&co1=AND&d=PTXT&s1=20140429.PD.&OS=ISD/20140429&RS=ISD/20140429

Keywords for this news article include: Samsung Electronics Co. Ltd.

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Source: Electronics Newsweekly


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