KR102429874B1 - Holographic display apparatus and holographic display method - Google Patents

Abstract

Disclosed are a holographic display device and a holographic display method capable of preventing binocular crosstalk. The disclosed holographic display device includes a spatial light modulator that forms a first hologram pattern and a second hologram pattern, and an illumination unit that provides light, and modulates incident light into a first hologram pattern and a second hologram pattern, respectively. The first phase modulation value of the first hologram pattern and the second phase modulation value of the second hologram pattern are set to be different from each other so that the holographic image and the second holographic image are formed at different positions in space.

Description

Holographic display apparatus and holographic display method {Holographic display apparatus and holographic display method}

The disclosed embodiments relate to a holographic display apparatus and a holographic display method, and more particularly, to a holographic display device capable of preventing binocular crosstalk while providing holographic images having different viewpoints to the left and right eyes of a viewer, respectively. It relates to a graphic display device and a holographic display method.

As a method of realizing a three-dimensional image, the glasses method and the glasses-free method are widely commercialized and used. The glasses method includes a polarized glasses method and a shutter glasses method, and the glasses-free method includes a lenticular method and a parallax barrier method. These methods use the binocular parallax of the two eyes, and there is a limit to the increase in the number of view points, and the depth perceived by the brain and the focus of the eyes do not match, making the viewer feel fatigued. do.

As a three-dimensional image display method capable of providing full parallax with the depth perceived by the brain and the focus of the eyes coincide, the holographic display method is gradually being put into practical use. The holographic display method uses the principle of reproducing the image of the original object by irradiating and diffracting the reference light to a hologram pattern in which the interference fringe obtained by interfering the reference light with the object light reflected from the original object is irradiated. The holographic display method currently being put into practical use provides a computer generated hologram (CGH) as an electrical signal to the spatial light modulator rather than directly exposing an original object to obtain a hologram pattern. The spatial light modulator forms a hologram pattern according to the input CGH signal and diffracts incident light to generate a three-dimensional image.

However, in order to implement a complete holographic display method, a spatial light modulator having a very high resolution and a very large data throughput are required. Recently, in order to alleviate the conditions of data throughput and resolution, a binocular hologram method in which holographic images are provided only to a viewing zone corresponding to both eyes of an observer has been proposed. For example, only a holographic image having a viewpoint corresponding to the observer's left eye field of view and a holographic image having a viewpoint corresponding to the observer's right eye field of view are generated and provided to the observer's left and right eyes, respectively. In this case, since it is not necessary to generate holographic images for the remaining viewpoints, the data throughput can be greatly reduced, and even a currently commercialized display device can satisfy the resolution condition of the spatial light modulator.

Provided are a holographic display apparatus and a holographic display method capable of preventing binocular crosstalk while providing holographic images having different viewpoints to a viewer's left and right eyes, respectively.

A holographic display apparatus according to an embodiment includes: a spatial light modulator for forming a hologram pattern for modulating incident light; an illumination unit providing light to the spatial light modulator; and a control unit for controlling the operation of the spatial light modulator and the lighting unit, wherein the spatial light modulator comprises a first hologram pattern and The control unit is configured to form a second hologram pattern, and the control unit controls the first phase modulation value of the first hologram pattern so that holographic images having different viewpoints formed by the first hologram pattern and the second hologram pattern are formed at different positions in space. and the second phase modulation value of the second hologram pattern may be set differently.

In order to alternately form the first hologram image and the second hologram image in a time division manner, the control unit controls the spatial light modulator to alternately scan the first hologram pattern and the second hologram pattern in a progressive scan manner. can

The spatial light modulator displays a first hologram pattern in a first frame and displays a second hologram pattern in a second frame subsequent to the first frame, wherein in a transition period between the first frame and the second frame, the spatial light A part of the first hologram pattern may be displayed on a partial region of the modulator and a part of the second hologram pattern may be displayed on the remaining partial region.

Here, the controller sets a first phase modulation value so that the first hologram image modulated by the first hologram pattern and formed during the transition period advances to the first viewing area, and the second hologram image modulated by the second hologram pattern The second phase modulation value may be set to proceed to a second viewing area different from the first viewing area.

In addition, the controller may control the spatial light modulator to overlap the first hologram pattern and the second hologram pattern to display them together in one frame.

Here, the control unit sets a first phase modulation value so that a first hologram image modulated by a first hologram pattern among the overlapping first and second hologram patterns advances in a first viewing area, and a second hologram pattern The second phase modulation value may be set so that the second hologram image modulated and formed by the .

For example, the lighting unit may include one light source unit providing light.

Here, the first phase modulation value may be set such that a first holographic image formed by modulating light emitted from the light source unit by a first hologram pattern is incident on a first viewing area, and the second phase modulation value is the light source unit The second holographic image formed by modulating light emitted from the second hologram pattern may be set to be incident on a second viewing area different from the first viewing area.

Alternatively, the lighting unit may include a first light source unit providing light for forming a first holographic image and a second light source unit providing light for forming a second holographic image.

For example, in the first phase modulation value, a first holographic image formed by modulating light emitted from the first light source unit by a first hologram pattern is incident on a first viewing area, and the light emitted from the second light source unit is The third holographic image modulated by the first hologram pattern may be set to be incident at a position deviated from the second viewing area.

In addition, the second phase modulation value is a second hologram image formed by modulating light emitted from the second light source unit by a second hologram pattern is incident on a second viewing area, and the light emitted from the first light source unit is a second The fourth holographic image modulated by the hologram pattern may be set to be incident at a position deviated from the first viewing area.

The holographic display device may further include a gaze tracking unit for tracking the position of the pupil of the observer, and the control unit is configured to correspond to the change in the position of the pupil of the observer, the position difference between the first holographic image and the fourth holographic image and the The first and second phase modulation values may be changed so that a position difference between the second holographic image and the third holographic image is maintained greater than the size of the observer's pupil.

The first light source unit and the second light source unit may be configured to provide light to the spatial light modulator together.

The first hologram pattern may be expressed as a product of hologram data of a first holographic image and a first phase modulation value, and the second hologram pattern may be expressed as a product of hologram data of a second holographic image and a second phase modulation value. have.

A holographic display apparatus according to another embodiment includes: a spatial light modulator for forming a hologram pattern for modulating incident light; an illumination unit providing light to the spatial light modulator; and a controller for controlling operations of the spatial light modulator and the lighting unit, wherein the spatial light modulator includes a first hologram pattern for modulating incident light into a first holographic image and a second hologram pattern for modulating incident light into a second holographic image. The control unit is configured to simultaneously form the first phase modulation value of the first hologram pattern and the difference between the position of the first holographic image and the position of the second holographic image to be maintained larger than the size of the observer's pupil. The second phase modulation value of the second hologram pattern may be set differently.

Meanwhile, a holographic display method according to another embodiment includes providing light to a spatial light modulator; and simultaneously forming, on the spatial light modulator, a first hologram pattern for modulating light into a first holographic image and a second hologram pattern for modulating light into a second holographic image. The first phase modulation value of the first hologram pattern and the second phase modulation value of the second hologram pattern are set differently so that the difference between the position of can

According to the disclosed holographic display apparatus and holographic display method, it is possible to effectively suppress binocular crosstalk while providing holographic images having different viewpoints to the left and right eyes of the observer, respectively. Therefore, when providing the holographic image for the left eye and the hologram image for the right eye in a time division manner, there is no need to insert an intermediate frame for preventing crosstalk between the frame of the holographic image for the left eye and the frame of the hologram image for the right eye. may improve the frame rate. In addition, it is possible to simultaneously provide the holographic image for the left eye and the hologram image for the right eye.

1 is a configuration diagram schematically showing the configuration of a holographic display device according to an embodiment.
2A and 2B exemplarily show the operation of the holographic display apparatus for providing holographic images having different viewpoints to the viewer's left eye and right eye areas according to a time division method.
3 exemplarily shows a process in which the spatial light modulator scans hologram patterns in a progressive scan method when providing a holographic image according to a time division method.
FIG. 4 exemplarily illustrates the operation of the holographic display apparatus for providing holographic images of different viewpoints to a viewer's left eye and right eye fields without binocular crosstalk during a transition period between frames.
5 exemplarily illustrates the operation of the holographic display apparatus for simultaneously providing holographic images having different viewpoints to the left eye and right eye fields of the observer.
6 exemplarily illustrates a process in which the spatial light modulator scans holographic patterns when simultaneously providing holographic images having different viewpoints to the left eye and right eye fields of the observer.
7 is a configuration diagram schematically showing the configuration of a holographic display device according to an embodiment.
8A and 8B exemplarily show the operation of the holographic display device illustrated in FIG. 7 for providing holographic images having different viewpoints to the viewer's left eye and right eye fields according to a time division method.
9A exemplarily illustrates the operation of the holographic display device in which the second light source unit of the holographic display device shown in FIG. 7 provides light to the spatial light modulator to generate a holographic image in the viewer's right eye field of view.
FIG. 9B exemplarily illustrates the operation of the holographic display device in which the first light source unit of the holographic display device shown in FIG. 7 provides light to the spatial light modulator to generate a holographic image in the viewer's left eye viewing area.
10 exemplarily illustrates a state in which holographic images of different viewpoints are provided to a viewer's left eye and right eye fields without binocular crosstalk.
11 exemplarily illustrates the operation of the holographic display apparatus for generating holographic images in the left eye field and right eye field of the observer by providing light to the spatial light modulator together with the first light source unit and the second light source unit.
12 is a timing diagram exemplarily illustrating an operation process of a lighting unit and a spatial light modulator in the operation method of the holographic display device shown in FIG. 11 .
13A, 13B, 14A and 14B show that crosstalk does not occur in the actually formed holographic image.
15 exemplarily illustrates the operation of the holographic display apparatus for simultaneously providing holographic images having different viewpoints to the left eye and right eye areas of the observer.
16 is a timing diagram exemplarily illustrating an operation process of a lighting unit and a spatial light modulator in the operation method of the holographic display device shown in FIG. 15 .

Hereinafter, a holographic display apparatus and a holographic display method will be described in detail with reference to the accompanying drawings. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description. In addition, the embodiments described below are merely exemplary, and various modifications are possible from these embodiments. In addition, in the layer structure described below, the expression "upper" or "upper" may include not only directly above in contact, but also above in non-contact.

1 is a configuration diagram schematically showing the configuration of a holographic display apparatus 100 according to an embodiment. The holographic display apparatus 100 according to the present embodiment includes a spatial light modulator 120 that forms a hologram pattern for modulating incident light, a lighting unit 110 that provides light to the spatial light modulator 120 , and a spatial light modulator. It may include a control unit 130 for controlling the operation of the 120 and the lighting unit (110). In addition, the holographic display apparatus 100 may further include a gaze tracking unit 150 for tracking the position of the observer's pupil.

The lighting unit 110 may include one light source unit that provides the focused light to the spatial light modulator 120 . Although not shown, the lighting unit 110 may further include a collimating lens for focusing the light. Alternatively, the lighting unit 110 may use a light source emitting focused light by itself. Then, all of the light emitted from the lighting unit 110 may be incident on the spatial light modulator 120 at an angle perpendicular to each other. Also, the lighting unit 110 may include a laser as a light source to provide light having high coherence. However, since light can be sufficiently diffracted and modulated by the spatial light modulator 120 if it has a certain degree of spatial coherence, it is also possible to use a light emitting diode (LED) as a light source. In addition to the light emitting diode, any other light source can be used as long as it emits light having spatial coherence. Although not shown in detail, one light source unit of the lighting unit 110 may be configured as an array of a plurality of light sources.

The spatial light modulator 120 may form a hologram pattern for diffracting and modulating incident light according to a hologram signal provided from the controller 130 . The spatial light modulator 120 may use any one of a phase modulator capable of performing only phase modulation, an amplitude modulator capable of performing only amplitude modulation, and a complex modulator capable of performing both phase and amplitude modulation. Although the spatial light modulator 120 is shown as a transmissive spatial light modulator in FIG. 1, it is also possible to use a reflective spatial light modulator. In the case of the transmissive type, the spatial light modulator 120 may use, for example, a semiconductor modulator based on a compound semiconductor such as GaAs, or a liquid crystal device (LCD). In the case of the reflective type, the spatial light modulator 120 may use, for example, a digital micromirror device (DMD), a liquid crystal on silicon (LCoS), or a semiconductor modulator.

The controller 130 may be configured to generate a hologram signal according to the holographic image to be provided to the observer, provide it to the spatial light modulator 120 , and control the operation of the lighting unit 110 . For example, the controller 130 may control turning on and off of the lighting unit 110 . The control unit 130 may be implemented using software, or may be implemented in the form of a semiconductor chip in which the function of such software is embedded.

The eye tracking unit 150 may obtain an image of the observer through a camera or the like, detect the pupil of the observer in the image, and analyze the position thereof. The eye tracking unit 150 may track a change in the observer's pupil position in real time and provide the result to the control unit 130 .

The holographic display apparatus 100 having the above-described structure may provide holographic images having different viewpoints to the left eye EL and the right eye ER of the observer in a binocular holographic method, respectively. For example, the holographic display apparatus 100 uses the gaze tracking unit 150 to determine the positions of the observer's left eye (EL) and right eye (ER), and displays the first holographic image in the observer's left eye (EL) viewing area. and may provide a second holographic image having a viewpoint different from that of the first holographic image to the viewing area of the observer's right eye (ER). To this end, the spatial light modulator 120 may form a first hologram pattern for the first hologram image and a second hologram pattern for the second hologram image under the control of the controller 130 .

For example, FIGS. 2A and 2B illustrate the operation of the holographic display apparatus 100 for providing holographic images having different viewpoints to the observer's left eye (EL) viewing area and right eye (ER) viewing area according to a time division method. is showing

First, referring to FIG. 2A , at a first time, the spatial light modulator 120 forms a first hologram pattern PL according to a hologram signal provided from the controller 130 . In addition, the lighting unit 110 provides light to the spatial light modulator 120 . Then, the object light may be reproduced while the light incident on the spatial light modulator 120 is diffracted and modulated by the first hologram pattern PL. As the object light reproduced in this way is projected on the viewer's left eye EL viewing area, a first holographic image L may be formed. Accordingly, at the first time, the observer can see the first holographic image L through the left eye EL.

Here, in order to accurately project the object light into the observer's left eye (EL) viewing area to form a first holographic image (L) in the observer's left eye (EL) viewing area, a phase modulation transfer function as shown in Equation 1 below transfer function) can be used.

Equation 1 above assumes that the spatial light modulator 120 is placed on the x-y plane. Also, in Equation 1, α is the angle between the incident light and the object light, and θ is the azimuth angle of the object light in the x-y plane.

The first hologram pattern PL may be expressed as a product (HL×tL) of the phase modulation value tL of the phase modulation transfer function represented by Equation 1 and the hologram data HL of the first holographic image L. . The hologram data is pre-made according to the image to be reproduced, and may be, for example, CGH data. That is, it can be seen that the hologram data includes information on the image to be reproduced, and the phase modulation value includes information on the position in the space where the reproduced image is projected. Accordingly, the first hologram pattern PL may include both information about an image to be reproduced and information about a location on which the image is to be projected. The phase modulation value may be set so that the first holographic image L formed by modulating the light emitted from the lighting unit 110 with the first hologram pattern PL is incident on the viewer's left eye EL viewing area. For example, the controller 130 may calculate the phase modulation value by determining the α value and the θ value according to the pupil position of the left eye EL of the observer provided by the gaze tracking unit 150 . The controller 130 may multiply the calculated phase modulation value with the CGH data of the image to create a hologram signal and provide it to the spatial light modulator 120 . In addition, the spatial light modulator 120 may form a first hologram pattern PL expressed as a product of a phase modulation value and hologram data according to a hologram signal. Then, the first holographic image L may be formed in the viewing area of the observer's left eye EL according to the phase modulation value of the first hologram pattern PL.

Next, referring to FIG. 2B , at a second time, the spatial light modulator 120 forms a second hologram pattern (PR=HR×tR) according to the hologram signal provided from the controller 130 . In addition, the lighting unit 110 provides light to the spatial light modulator 120 . Then, the object light may be reproduced while the light incident on the spatial light modulator 120 is diffracted and modulated by the second hologram pattern PR. As the object light reproduced in this way is projected onto the viewer's right eye ER, a second holographic image R may be formed. Accordingly, at the second time, the observer can see the second holographic image R through the right eye RL.

As described above, in order to accurately project the object light onto the observer's right eye (ER) viewing area to form a second holographic image (R) in the observer's right eye (ER) viewing area, the phase modulation transfer function expressed by Equation 1 may be used. can For example, the controller 130 may calculate the phase modulation value by determining the α value and the θ value according to the pupil position of the right eye ER of the observer provided by the eye tracking unit 150 . The controller 130 may multiply the calculated phase modulation value with the CGH data of the image to create a hologram signal and provide it to the spatial light modulator 120 . In addition, the spatial light modulator 120 may form a second hologram pattern PR expressed as a product of a phase modulation value and hologram data according to the hologram signal. According to the phase modulation value of the second hologram pattern PR, the second holographic image R may be formed in the viewing area of the viewer's right eye ER.

Meanwhile, in the case of the time division method, it is common that the spatial light modulator 120 alternately scans the first hologram pattern PL and the second hologram pattern PR in a progressive scan method. For example, FIG. 3 shows that when the first and second hologram images L and R are alternately formed according to the time division method, the spatial light modulator 120 sequentially generates the first and second hologram patterns PL and PR. The injection process is illustrated by way of example. Referring to FIG. 3 , the spatial light modulator 120 displays a first hologram pattern PL in a first frame, and displays a second hologram pattern PR in a second frame subsequent to the first frame, , in the third frame following the second frame, the first hologram pattern PL may be displayed again. Here, the first hologram pattern PL of the first frame and the second hologram pattern PR of the second frame may have different viewpoint information for the same image. Also, the first hologram pattern PL of the first frame and the first hologram pattern PL of the third frame may have the same viewpoint and temporally continuous image information.

However, in the transition period between frames, the two hologram patterns PL and PR may be simultaneously displayed on the spatial light modulator 120 . For example, in the transition period T1 between the first frame and the second frame, a part of the first hologram pattern PL is displayed in a partial region of the spatial light modulator 120 , and the A portion of the second hologram pattern PR may be displayed in the remaining partial area. Similarly, in the transition period T2 between the second frame and the third frame, a part of the second hologram pattern PR is displayed in a partial area of the spatial light modulator 120 , and a part of the remaining partial area of the spatial light modulator 120 is displayed. A part of the first hologram pattern PL may be displayed.

Accordingly, if the first hologram pattern PL and the second hologram pattern PR have the same phase modulation value, the first hologram image L is displayed in the viewing region of the observer's right eye ER in the transition periods T1 and T2. A binocular crosstalk may occur, in which either the holographic image R is formed or the second holographic image R is formed in the viewer's left eye EL viewing area. In order to prevent the binocular crosstalk phenomenon, the control unit 130 of the holographic display apparatus 100 according to the present embodiment determines the time points respectively reproduced by the first hologram pattern PL and the second hologram pattern PR. The first phase modulation value tL of the first hologram pattern PL and the second phase modulation value tR of the second hologram pattern PR may be set differently so that different holographic images are formed at different positions in space. have.

For example, FIG. 4 is a holographic display device that provides holographic images L and R from different viewpoints to the left eye (EL) and right eye (ER) viewing regions of the observer without binocular crosstalk during the transition period between frames. The operation of (100) is shown as an example. Referring to FIG. 4 , a first hologram pattern PL is formed in a lower region of the spatial light modulator 120 and a second hologram pattern PR is formed in an upper region of the spatial light modulator 120 . The controller 130 may set the first phase modulation value tL so that the first holographic image L formed by the first hologram pattern PL proceeds only in the observer's left eye EL viewing area, and the second The second phase modulation value tR may be set to be different from the first phase modulation value tL so that the second holographic image R formed by the hologram pattern PR proceeds only in the viewing area of the observer's right eye ER. . Accordingly, it is possible to provide the holographic images L and R from different viewpoints to the left eye (EL) field of view and the right eye (ER) field of view of the observer without binocular crosstalk even during the transition period between frames.

The holographic display apparatus 100 may alternately form the first hologram image L and the second hologram image R in a time division manner as described above, but due to the characteristics of the hologram, the first hologram pattern PL and the second It is also possible to form the first holographic image L and the second holographic image R together by overlapping the hologram patterns PR. For example, FIG. 5 shows an operation of the holographic display apparatus 100 for simultaneously providing first and second holographic images L and R having different viewpoints to the observer's left eye (EL) viewing area and right eye (ER) viewing area. is shown as an example. Referring to FIG. 5 , the spatial light modulator 120 superimposes a first hologram pattern (PL=HL×tL) and a second hologram pattern (PR=HR×tR) according to a hologram signal provided from the controller 130 , They are displayed together in one frame.

In addition, FIG. 6 shows that when the first and second hologram images L and R having different viewpoints are simultaneously provided to the left eye (EL) and right eye (ER) viewing regions of the observer, the spatial light modulator 120 performs the first and A process of scanning the second hologram patterns PL and PR is exemplarily shown. Referring to FIG. 6 , the spatial light modulator 120 includes first and second overlapping hologram patterns PL1 and PR1 of a first frame and first and second overlapping hologram patterns PL2 and PR2 of a second frame. , the first and second overlapping hologram patterns PL3 and PR3 of the third frame may be scanned in a progressive scan method, respectively.

Referring back to FIG. 5 , even when the first hologram pattern PL and the second hologram pattern PR are overlapped and displayed together in one frame, the first phase modulation value tL of the first hologram pattern PL By differentiating the second phase modulation value tR of the second hologram pattern PR and the second hologram pattern PR, it is possible to prevent binocular crosstalk. For example, when the light emitted from the lighting unit 110 is modulated by the first hologram pattern PL and the second hologram pattern PR displayed together on the spatial light modulator 120 , the first holographic image L ) and the second holographic image R are respectively formed. Here, the first phase modulation value tL of the first hologram pattern PL is selected such that the first holographic image L faces the viewer's left eye EL viewing area, and the second hologram image L of the second hologram pattern PR The phase modulation value tR may be selected such that the second holographic image R faces the viewing area of the observer's right eye ER. Accordingly, it is possible to simultaneously form the first holographic image L and the second holographic image R without crosstalk.

So far, it has been described that the lighting unit 110 includes one light source unit. In order to respectively form the first holographic image L and the second holographic image R using only one light source unit, the pixel pitch of the spatial light modulator 120 is sufficiently small that the resolution of the spatial light modulator 120 is high. It is advantageous. However, when the lighting unit 110 uses two light source units, the resolution condition of the spatial light modulator 120 may be relaxed.

For example, FIG. 7 is a configuration diagram schematically illustrating a configuration of a holographic display apparatus 200 according to another exemplary embodiment. Referring to FIG. 7 , the holographic display apparatus 200 according to the present embodiment includes a spatial light modulator 120 that forms a hologram pattern for modulating light, and a lighting unit 110 that provides light to the spatial light modulator 120 . ), and a control unit 130 for controlling the operations of the spatial light modulator 120 and the lighting unit 110 . In addition, the holographic display apparatus 200 may further include a gaze tracking unit 150 for tracking the position of the pupil of the observer.

The lighting unit 110 may include a first light source unit 110L for a holographic image to be formed in the viewer's left eye EL and a second light source unit 110R for a holographic image to be formed in the viewer's right eye ER. The first and second light source units 110L and 110R may be arranged to provide light incident to the spatial light modulator 120 at different angles obliquely from each other. For example, the first light source unit 110L is disposed opposite to the viewer's left eye EL with respect to the center of the spatial light modulator 120 , and the second light source unit 110R is the spatial light modulator 120 . It may be disposed opposite to the observer's right eye (ER) with respect to the center. The first and second light sources 110L and 110R may be lasers or arrays of LEDs capable of providing light having spatial coherence.

In addition, the holographic display apparatus 200 may further include a lens 140 for focusing the reproduced light formed by modulating light by the spatial light modulator 120 in a predetermined space. A holographic image may be formed in a space by focusing the reproduced light on a predetermined space by the lens 140 . Although the lens 140 is illustrated as being disposed between the lighting unit 110 and the spatial light modulator 120 in FIG. 7 , the present invention is not limited thereto. For example, the lens 140 may be disposed on the front surface of the spatial light modulator 120 , that is, between the spatial light modulator 120 and the observer. In addition, if the lighting unit 110 provides the focused light, the lens 140 may be omitted.

For example, FIGS. 8A and 8B illustrate the holographic display apparatus 200 shown in FIG. 7 that provides holographic images having different viewpoints to the observer's left eye (EL) viewing area and right eye (ER) viewing area according to a time division method, respectively. The operation is shown as an example.

First, referring to FIG. 8A , at a first time, the spatial light modulator 120 forms a first hologram pattern PL according to a hologram signal provided from the controller 130 . In addition, the first light source unit 110L provides light to the spatial light modulator 120 according to the control of the controller 130 . Then, the object light may be reproduced while the light from the first light source unit 110L is diffracted and modulated by the first hologram pattern PL. As the object light reproduced in this way is projected on the viewer's left eye EL viewing area, a first holographic image L may be formed. Accordingly, at the first time, the observer can see the first holographic image L through the left eye EL.

As described above, in order to accurately project the object light onto the observer's left eye (EL) viewing area to form the first holographic image (L) in the observer's left eye (EL) viewing area, a phase modulation transfer function as shown in Equation 1 may be used. can That is, the first hologram pattern PL may be expressed as the product (HL×tL) of the phase modulation value tL of the phase modulation transfer function represented by Equation 1 and the hologram data HL of the first holographic image L. can The phase modulation value may be set such that the first holographic image L formed by modulating the light emitted from the first light source unit 110L with the first hologram pattern PL is incident on the viewer's left eye EL viewing area. .

Next, referring to FIG. 8B , at a second time, the spatial light modulator 120 forms a second hologram pattern (PR=HR×tR) according to the hologram signal provided from the controller 130 . In addition, the second light source unit 110R provides light to the spatial light modulator 120 according to the control of the controller 130 . Then, the object light may be reproduced while the light is diffracted and modulated by the second hologram pattern PR. As the object light reproduced in this way is projected onto the viewer's right eye ER, a second holographic image R may be formed. Accordingly, at the second time, the observer can see the second holographic image R through the right eye RL.

Here, the phase modulation transfer function expressed by Equation 1 may be used to accurately project the object light onto the viewer's right eye (ER) viewing area to form the second holographic image R in the observer's right eye (ER) viewing area. That is, the second hologram pattern PR is expressed as the product (HR×tR) of the phase modulation value tR of the phase modulation transfer function represented by Equation 1 and the hologram data HR of the second holographic image R. can The phase modulation value is, for example, set so that the second holographic image R formed by modulating the light emitted from the second light source unit 110R with the second hologram pattern PR is incident on the viewer's right eye ER viewing area. can be

However, as already described in FIG. 3 , when the spatial light modulator 120 alternately scans the first hologram pattern PL and the second hologram pattern PR in a progressive scan method, transition between frames During the period, the two hologram patterns PL and PR may be simultaneously displayed on the spatial light modulator 120 . Accordingly, if the first hologram pattern PL and the second hologram pattern PR have the same phase modulation value, the first hologram image L is displayed in the viewing region of the observer's right eye ER in the transition periods T1 and T2. A binocular crosstalk may occur, in which either the holographic image R is formed or the second holographic image R is formed in the viewer's left eye EL viewing area. For example, in the transition period T1 between the first frame and the second frame, assuming that the second light source unit 110R provides light to the spatial light modulator 120 as shown in FIG. 8B , the spatial light Images having different viewpoints respectively formed by the second hologram pattern PR and the first hologram pattern PL displayed on the modulator 120 may be formed in the viewing region of the observer's right eye ER. Also, in the transition period T2 between the second frame and the third frame, assuming that the first light source unit 110L provides light to the spatial light modulator 120 as shown in FIG. 8A, the spatial light modulator 120 ), images having different viewpoints formed by the first hologram pattern PL and the second hologram pattern PR may all be formed in the viewer's left eye EL viewing area.

In order to prevent the binocular crosstalk phenomenon, the control unit 130 of the holographic display apparatus 200 according to the present embodiment has different viewpoints formed by the first hologram pattern PL and the second hologram pattern PR, respectively. The first phase modulation value tL of the first hologram pattern PL and the second phase modulation value tR of the second hologram pattern PR may be set differently so that the holographic images are formed at different positions in space. . For example, FIG. 9A illustrates an operation of the holographic display apparatus 200 in which the second light source unit 110R provides light to the spatial light modulator 120 to generate a holographic image in the viewer's right eye (ER) viewing area. 9B illustrates the operation of the holographic display apparatus 200 in which the first light source unit 110L provides light to the spatial light modulator 120 to generate a holographic image in the viewer's left eye (EL) viewing area. It is shown hostilely.

First, referring to FIG. 9A , in the transition period T1 between the first frame and the second frame, the second light source unit 110R provides light to the spatial light modulator 120 . In this case, a part of the second hologram pattern PR may be displayed in a partial area of the spatial light modulator 120 , and a part of the first hologram pattern PL may be displayed in the remaining partial area. Then, the light emitted from the second light source unit 110R is incident on both the second hologram pattern PR and the first hologram pattern PL. Accordingly, the light emitted from the second light source unit 110R is modulated by the second hologram pattern PR and the first hologram pattern PL, respectively, so that the second and third holographic images R and L′ from different viewpoints are generated. are formed together Here, the second holographic image R is a normal image, but the third holographic image L' is an abnormal image that causes crosstalk in the viewer's right eye (ER) viewing area. The controller 130 sets the second phase modulation value tR of the second hologram pattern PR so that the normal second hologram image R is accurately incident on the viewer's right eye ER viewing area. And, in order to prevent crosstalk, the controller 130 controls the first phase modulation value ( tL) is set. Then, as shown in FIG. 9A , since only the second hologram image R is incident on the viewer's right eye ER, crosstalk can be prevented.

Also, referring to FIG. 9B , in the transition period T2 between the second frame and the third frame, the first light source unit 110L provides light to the spatial light modulator 120 . In this case, a portion of the first hologram pattern PL may be displayed in a partial area of the spatial light modulator 120 , and a portion of the second hologram pattern PR may be displayed in the remaining partial area. Then, the light emitted from the first light source unit 110L is incident on both the first hologram pattern PL and the second hologram pattern PR. Accordingly, the light emitted from the first light source unit 110L is modulated by the first hologram pattern PL and the second hologram pattern PR, respectively, so that the first and fourth holographic images L and R' from different viewpoints are generated. are formed together Here, the first holographic image L is a normal image, but the fourth holographic image R' is an abnormal image that induces crosstalk in the viewer's left eye EL viewing area. The controller 130 sets the first phase modulation value tL of the first hologram pattern PL so that the normal first hologram image L is accurately incident on the viewer's left eye EL viewing area. And, in order to prevent crosstalk, the controller 130 controls the second phase modulation value ( tR) is set. Then, as shown in FIG. 9B , since only the first hologram image L is incident on the viewer's left eye EL viewing area, crosstalk can be prevented.

As a result, the first phase modulation value tL is a normal first holographic image L formed by modulating the light emitted from the first light source unit 110L by the first hologram pattern PL is the left eye EL of the observer. ), an abnormal third holographic image L' formed by modulating light emitted from the second light source unit 110R by the first hologram pattern PL is located outside the viewing area of the observer's right eye ER. It can be set to enter. In addition, the second phase modulation value tR is a normal second holographic image R formed by modulating light emitted from the second light source unit 110R by the second hologram pattern PR, which is the observer's right eye ER. An abnormal fourth holographic image R′, which is incident on the viewing area and formed by modulating light emitted from the first light source 110L by the second hologram pattern PR, is incident at a position out of the observer's left eye EL viewing area. can be set to Here, the first hologram pattern PL is expressed as a product (HL×tL) of the hologram data HL of the first hologram image L and the first phase modulation value tL, and the second hologram pattern PR may be expressed as a product (HR×tR) of the hologram data HR of the second holographic image R and the second phase modulation value tR.

Then, as shown in FIG. 10, only the normal first holographic image L and the second holographic image R are incident on the pupil of the observer's left eye EL and the pupil of the right eye ER, respectively, to be recognized by the observer. can On the other hand, since the abnormal third holographic image L' and the fourth holographic image R' deviate from the pupil of the observer's right eye (ER) and the pupil of the left eye (EL), respectively, they are not recognized by the observer, thereby preventing crosstalk. can do.

As described above, the light emitted from the fourth holographic image R′ and the second light source 110R formed by modulating the light emitted from the first light source 110L by the second hologram pattern PR is the first Since crosstalk due to the third holographic image L′ modulated by the hologram pattern PL does not occur, there is no need to alternately turn on the first light source unit 110R and the second light source unit 110R. For example, in FIG. 11 , the first light source unit 110L and the second light source unit 110R together provide light to the spatial light modulator 120 to display a holographic image ( The operation of the holographic display apparatus 200 for generating each of L and R) is illustrated by way of example. Also, FIG. 12 is a timing diagram exemplarily illustrating an operation process of the lighting unit 110 and the spatial light modulator 120 in the operation method of the holographic display apparatus 200 shown in FIG. 11 .

11 and 12 , even when the first light source unit 110R and the second light source unit 110R provide light to the spatial light modulator 120 together, the normal first holographic image L and the second hologram The image R may be recognized by the observer by accurately entering the pupil of the left eye EL and the pupil of the right eye ER of the observer, respectively. On the other hand, the abnormal third holographic image L' is not recognized by the observer because it deviates from the pupil of the observer's right eye ER. In addition, the abnormal fourth holographic image R' may not be recognized by the observer because it also deviates from the observer's left eye EL pupil.

Accordingly, since there is no need to alternately operate the first light source unit 110R and the second light source unit 110R in synchronization with the frame period of the spatial light modulator 120, the configuration of the holographic display apparatus 200 can be simplified. . Also, according to the present embodiment, when the first holographic image L and the second holographic image R are provided in a time division manner, the frame of the first holographic image L and the frame of the second holographic image R Since there is no need to insert an intermediate frame for preventing crosstalk therebetween, the image reproduction speed (frame rate) of the holographic display apparatus 200 may be improved.

On the other hand, when the position of the pupil is changed due to the movement of the observer's gaze, the controller 130 calculates the first and second phase modulation values in response to the change in the position of the pupil of the observer based on the information provided from the gaze tracking unit 150 . can change The controller 130 may reset the first and second phase modulation values so that crosstalk is not induced even when the first and second phase modulation values are changed according to a change in the position of the pupil of the observer. For example, in response to a change in the observer's pupil position, the controller 130 may control a position difference between the first holographic image L and the fourth holographic image R' and the second holographic image R and the third hologram image. The first and second phase modulation values may be changed so that a position difference between the images L′ is maintained to be greater than the size of the observer's pupil.

13A, 13B, 14A and 14B show that crosstalk does not occur in the actually formed hologram image. 13A, 13B, 14A and 14B, in order to confirm that crosstalk can be eliminated in the above-described manner, a holographic image is actually formed, and a camera is provided in the left eye (EL) field of view and the right eye field of view (ER), respectively. It is the result of taking a holographic image by placing Specifically, FIG. 13A is a result of capturing a first holographic image L having a depth of +100 mm with a camera in the left eye (EL) viewing area, and FIG. 13B is a second holographic image R having a depth of +100 mm. is the result taken with a camera in the right eye (ER) viewing area. 14A is a result of shooting a first holographic image L having a depth of 0 mm with a camera in the left eye (EL) viewing area, and FIG. 14B is a second holographic image R having a depth of 0 mm to the right eye ( ER) This is the result taken with a camera in the field of view. As shown in FIGS. 13A, 13B, 14A and 14B , crosstalk was not detected in any images captured by cameras disposed in the left eye (EL) and right eye (ER), respectively.

Although the holographic display method of alternately forming the first hologram image L and the second hologram image R in a time division method has been described, the first hologram pattern PL and the second hologram pattern PR due to the characteristics of the hologram ), it is also possible to form the first holographic image L and the second holographic image R together. 15 exemplarily illustrates the operation of the holographic display apparatus 200 for simultaneously providing first and second holographic images L and R having different viewpoints to the viewer's left eye (EL) and right eye (ER) viewing areas. is showing Also, FIG. 16 is a timing diagram illustrating an operation process of the lighting unit 110 and the spatial light modulator 120 in the operation method of the holographic display apparatus 200 shown in FIG. 15 . 15 and 16 , the spatial light modulator 120 superimposes the first hologram pattern PL and the second hologram pattern PR according to the hologram signal provided from the controller 130 and displays them together in one frame. are doing

For example, as shown in FIG. 6 , the spatial light modulator 120 includes first and second overlapping hologram patterns PL1 and PR1 in a first frame, and first and second overlapping holograms in a second frame. The patterns PL2 and PR2 and the overlapping first and second hologram patterns PL3 and PR3 of the third frame may be scanned in a progressive scan method, respectively.

Referring back to FIG. 15 , even when the first hologram pattern PL and the second hologram pattern PR are overlapped and displayed together in one frame, the first phase modulation value of the first hologram pattern PL and the second By varying the second phase modulation value of the hologram pattern PR, binocular crosstalk may be prevented. For example, when the light emitted from the first light source unit 110L is modulated by the first hologram pattern PL and the second hologram pattern PR displayed together on the spatial light modulator 120, respectively, the first holographic image (L) and a fourth holographic image (R') are respectively formed. Here, the first phase modulation value of the first hologram pattern PL is selected such that the first holographic image L faces the viewing region of the observer's left eye EL, and the second phase modulation value of the second hologram pattern PR (tR) may be selected so that the fourth holographic image R′ deviates from the viewer's left eye EL viewing area. In addition, when the light emitted from the second light source unit 110R is modulated by the first hologram pattern PL and the second hologram pattern PR displayed together on the spatial light modulator 120, respectively, the third holographic image L ') and the second holographic image R are respectively formed. Here, the first phase modulation value tL of the first hologram pattern PL is selected so that the third hologram image L' is deviated from the viewing area of the observer's right eye ER, and the second hologram image L' of the second hologram pattern PR The second phase modulation value may be selected so that the second holographic image R faces the viewer's right eye (ER) viewing area. Accordingly, it is possible to simultaneously form the first holographic image L and the second holographic image R without crosstalk.

In the above-described embodiments, the controller 130 crosses the first phase modulation value tL of the first hologram pattern PL and the second phase modulation value tR of the second hologram pattern PR. torque can be avoided. As described above, since the control unit 130 may be implemented using software or may be implemented in the form of a semiconductor chip in which the function of such software is embedded, an additional mechanical or electronic device is required to prevent crosstalk. it may not be

In the above description, a case has been described in which the holographic display apparatuses 100 and 200 respectively form two holographic images L and R having different viewpoints in two viewing regions having different positions in space. However, it is also possible to form holographic images having three or more different viewpoints in three or more different viewing regions, respectively. For example, the spatial light modulator 120 may sequentially or overlap three or more hologram patterns at the same time, and the controller 130 may set different phase modulation values of the three or more hologram patterns, respectively. Here, the controller 130 may set the phase modulation values such that the interval between three or more different viewing zones is maintained to be larger than the size of the observer's pupil. For example, the controller 130 controls the phase modulation value of each hologram pattern so that the position difference between the three or more holographic images at different times of reproduction by the three or more hologram patterns is maintained greater than the size of the observer's pupil. can be set.

Up to now, exemplary embodiments of a holographic display device and a holographic display method have been described and shown in the accompanying drawings in order to help the understanding of the technical principle. However, it should be understood that these embodiments are merely illustrative of the technical principles and do not limit them. And it should be understood that the scope of the patent is not limited to the description shown and described. This is because various other modifications may occur to those skilled in the art.

100, 200.....Holographic display device
110.....Lighting part 110L, 110R.....Light source part
120.....Spatial Light Modulator 130.....Control Unit
140.....Lens 150.....Eye tracking unit

Claims (27)

a spatial light modulator for forming a hologram pattern for modulating incident light;
an illumination unit providing light to the spatial light modulator; and
a control unit for controlling the operation of the spatial light modulator and the lighting unit;
In order to provide a first hologram image and a second hologram image having different viewpoints, the spatial light modulator is configured to form a first hologram pattern and a second hologram pattern under the control of the controller,
The controller controls the first phase modulation value of the first hologram pattern and the second hologram image so that the first and second hologram images having different viewpoints formed by the first hologram pattern and the second hologram pattern are formed at different positions in space. setting the second phase modulation value of the pattern differently,
The first hologram pattern is expressed as a product of hologram data of a first holographic image and a first phase modulation value, and the second hologram pattern is expressed as a product of hologram data of a second holographic image and a second phase modulation value,
The first and second phase modulation values are values of phase transfer functions for forming the first and second holographic images at different positions in space, respectively. The method of claim 1,
In order to alternately form the first hologram image and the second hologram image in a time division manner, the control unit controls the spatial light modulator to alternately scan the first hologram pattern and the second hologram pattern in a progressive scan manner. Holographic display device. 3. The method of claim 2,
The spatial light modulator displays a first hologram pattern in a first frame and displays a second hologram pattern in a second frame subsequent to the first frame, wherein in a transition period between the first frame and the second frame, the spatial light A holographic display device configured to display a portion of the first hologram pattern on a partial area of the modulator and display a portion of the second hologram pattern on the remaining partial area. 4. The method of claim 3,
The controller sets a first phase modulation value so that a first hologram image modulated by the first hologram pattern and formed during the transition period advances in the first viewing area, and the second hologram image modulated by the second hologram pattern is converted to a first A holographic display device for setting a second phase modulation value to proceed to a second viewing area different from the viewing area. The method of claim 1,
The control unit controls the spatial light modulator to overlap the first hologram pattern and the second hologram pattern to display them together in one frame. 6. The method of claim 5,
The control unit sets a first phase modulation value so that a first holographic image modulated by a first hologram pattern from among the overlapping first and second hologram patterns advances in a first viewing area, and by the second hologram pattern A holographic display apparatus for setting a second phase modulation value so that the modulated second holographic image progresses in a second viewing area different from the first viewing area. The method of claim 1,
The lighting unit includes a single light source for providing light. 8. The method of claim 7,
The first phase modulation value is set so that a first holographic image formed by modulating light emitted from the light source unit by a first hologram pattern is incident on a first viewing area, and the second phase modulation value is the light emitted from the light source unit A holographic display apparatus configured to cause a second holographic image modulated by the second hologram pattern to be incident on a second viewing area different from the first viewing area. The method of claim 1,
The illumination unit includes a first light source unit providing light for forming a first holographic image and a second light source unit providing light for forming a second holographic image. 10. The method of claim 9,
The first phase modulation value is a first holographic image formed by modulating light emitted from the first light source by a first hologram pattern is incident on a first viewing area, and the light emitted from the second light source is generated by a first hologram pattern A holographic display device that is set so that the third holographic image modulated by the is incident at a position out of the second viewing area. 11. The method of claim 10,
The second phase modulation value is a second hologram image formed by modulating the light emitted from the second light source by a second hologram pattern is incident on a second viewing area, and the light emitted from the first light source is generated by the second hologram pattern. A holographic display device that is set so that the fourth holographic image modulated by the is incident at a position out of the first viewing area. 12. The method of claim 11,
Further comprising a gaze tracking unit for tracking the position of the pupil of the observer,
The controller maintains a position difference between the first holographic image and a fourth holographic image and a position difference between the second holographic image and the third holographic image in response to a change in the observer's pupil position to be greater than the observer's pupil size A holographic display device for changing the first and second phase modulation values as much as possible. 10. The method of claim 9,
The first light source unit and the second light source unit are configured to provide light to the spatial light modulator together. delete a spatial light modulator for forming a hologram pattern for modulating incident light;
an illumination unit providing light to the spatial light modulator; and
a control unit for controlling the operation of the spatial light modulator and the lighting unit;
The spatial light modulator is configured to simultaneously form a first hologram pattern for modulating incident light into a first holographic image and a second hologram pattern for modulating incident light into a second holographic image,
The control unit is configured to maintain a first phase modulation value of the first hologram pattern and a second value of the second hologram pattern so that a difference between the position of the first hologram image and the position of the second hologram image is maintained greater than the size of the observer's pupil. Set different phase modulation values,
The first hologram pattern is expressed as a product of hologram data of a first holographic image and a first phase modulation value, and the second hologram pattern is expressed as a product of hologram data of a second holographic image and a second phase modulation value,
The first and second phase modulation values are values of phase transfer functions for forming the first and second holographic images at different positions in space, respectively. 16. The method of claim 15,
The lighting unit includes a single light source for providing light. 17. The method of claim 16,
The first phase modulation value is set so that a first holographic image formed by modulating light emitted from the light source unit by a first hologram pattern is incident on a first viewing area, and the second phase modulation value is the light emitted from the light source unit A holographic display apparatus configured to cause a second holographic image modulated by the second hologram pattern to be incident on a second viewing area different from the first viewing area. 16. The method of claim 15,
The illumination unit includes a first light source unit providing light for forming a first holographic image and a second light source unit providing light for forming a second holographic image. 19. The method of claim 18,
The first phase modulation value is a first holographic image formed by modulating light emitted from the first light source by a first hologram pattern is incident on a first viewing area, and the light emitted from the second light source is generated by a first hologram pattern A holographic display device that is set so that the third holographic image modulated by the is incident at a position out of the second viewing area. 20. The method of claim 19,
The second phase modulation value is a second hologram image formed by modulating the light emitted from the second light source by a second hologram pattern is incident on a second viewing area, and the light emitted from the first light source is generated by the second hologram pattern. A holographic display device that is set so that the fourth holographic image modulated by the is incident at a position out of the first viewing area. 21. The method of claim 20,
The control unit controls first and second phase modulation values so that a position difference between the first holographic image and a fourth holographic image and a position difference between the second holographic image and the third holographic image are maintained greater than the size of the observer's pupil. Holographic display device to set. providing light to a spatial light modulator; and
Forming a first hologram pattern for modulating light into a first holographic image and a second hologram pattern for modulating light into a second holographic image simultaneously on the spatial light modulator;
The first phase modulation value of the first hologram pattern and the second phase modulation of the second hologram pattern so that a difference between the position of the first holographic image and the position of the second hologram image is maintained greater than the size of the observer's pupil value is set differently,
The first hologram pattern is expressed as a product of hologram data of a first holographic image and a first phase modulation value, and the second hologram pattern is expressed as a product of hologram data of a second holographic image and a second phase modulation value,
The first and second phase modulation values are values of phase transfer functions for forming the first and second holographic images at different positions in space, respectively. 23. The method of claim 22,
The step of providing light to the spatial light modulator is performed using one light source unit,
The first phase modulation value is set so that a first holographic image modulated by the first hologram pattern is incident on a first viewing area, and the second phase modulation value is a second phase modulation value modulated by the second hologram pattern. A holographic display method in which the holographic image is set to be incident on a second viewing area different from the first viewing area. 23. The method of claim 22,
The step of providing light to the spatial light modulator is performed using a first light source unit providing light for forming a first holographic image and a second light source unit providing light for forming a second holographic image,
The first phase modulation value is a first holographic image formed by modulating light emitted from the first light source unit by a first hologram pattern to be incident on a first viewing area, and light emitted from the second light source unit to a first hologram pattern. A holographic display method in which a third holographic image modulated and formed by a holographic display is set to be incident at a position deviated from the second viewing area. 25. The method of claim 24,
The second phase modulation value is a second holographic image formed by modulating the light emitted from the second light source by a second hologram pattern is incident on a second viewing area, and the light emitted from the first light source is in the second hologram pattern. A holographic display method in which a fourth holographic image modulated and formed by a holographic display is set to be incident at a position deviated from the first viewing area. 26. The method of claim 25,
The first and second phase modulation values are set so that the position difference between the first holographic image and the fourth holographic image and the position difference between the second holographic image and the third holographic image are maintained to be greater than the size of the observer's pupil. A holographic display method. delete

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