Patent ID: 12235549

DETAILED DESCRIPTION

Features and exemplary embodiments of various aspects of the disclosure are described in detail below. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the present disclosure by illustrating examples of the present disclosure.

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of this disclosure can be combined with each other. The embodiments will be described in detail below with reference to the accompanying drawings.

Relational terms, such as first, or second, etc., are used only to distinguish one entity or operation from another entity or operation and do not necessarily require or imply that any such actual relationship exists between these entities or operations or order. Furthermore, the terms “comprises”, “includes”, or any other variations thereof are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also those not expressly listed other elements, or elements inherent to the process, method, article or equipment. Without further limitation, an element defined by the statement “comprising . . . ” does not exclude the presence of additional identical elements in a process, method, article, or device that includes the stated element.

It will be understood that when describing the structure of components, when one layer or region is referred to as being “on” or “over” another layer or region, it may mean that it is directly on the other layer or region, or is directly on the other layer or region. There are other layers or areas between it and another layer, another area, and if the part is turned over, that layer, one area, will be “under” or “below” another layer, or area.

In addition, the term “and/or” in this disclosure is only an association relationship that describes related objects, indicating that there can be three relationships. For example, A and/or B may mean three cases: A alone exists, A and B exist simultaneously, and B alone. In addition, the character “/” in this article generally indicates that the related objects are an “or” relationship.

It should be understood that in the embodiment of the present disclosure, “B corresponding to A” may mean that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B only based on A, B can also be determined based on A and/or other information.

It has been found that, in a three-dimensional display device, the display light emitted by the light-emitting device will adjust the phase and amplitude of the light through the spatial light modulator. The adjusted light is emitted from the polarizer, and a display from zero brightness to full brightness can be achieved. Spatial light modulators typically take the form of liquid crystal panels. The external ambient light will be incident from the light-exiting side of the three-dimensional display device, reflected at the liquid crystal panel of the spatial light modulator, and then emitted from the light-exiting side of the three-dimensional display device again. Therefore, the reflected ambient light will cross-talk with the modulated display light, affecting the display effect of the three-dimensional display device. To reduce the impact of reflected light from ambient light on the display effect, quarter-wave plates are sequentially installed on the light-exiting side of the LCD. However, the display light will be deflected after passing through the quarter-wave plate, and the transmittance of the polarizer will be affected, making the brightness range of the light after passing through the polarizer reduced, and making it difficult to meet the maximum expected transmittance and the minimum expected transmittance.

The present disclosure provides a spatial light modulator and a holographic three-dimensional display device. The spatial light modulator may include a first liquid crystal panel, a second liquid crystal panel, a quarter-wave plate and a polarizer. The first light may pass through the first liquid crystal panel, the second liquid crystal panel, the quarter-wave plate and the polarizer in sequence, and then may emit from the spatial light modulator. The external light may form polarized light after passing through the polarizer. After passing through the quarter-wave plate, the polarization direction may be rotated. After being reflected at the second liquid crystal panel, the polarization direction may be rotated again after passing through the quarter-wave plate, and may intersect the polarization directions of the polarizers, making it difficult to transmit through the polarizer, thereby reducing the impact of external light reflected on the second liquid crystal panel on the exiting light. The difference between the refractive index of the second liquid crystal molecules along the optical axis of the liquid crystal and the refractive index perpendicular to the optical axis of the liquid crystal may be Δn, the thickness of the second liquid crystal layer may be d, the wavelength of the first light may be λ1, and 0.5λ1≤Δn×d≤0.75λ1. When the second liquid crystal panel adjusts the first light, the maximum brightness of the first light may be increased while keeping the minimum brightness of the first light unchanged. Thus, the display effect of the holographic three-dimensional display device may be enhanced.

FIG.1illustrates a schematic structural diagram of an exemplary spatial light modulator according to various embodiments of the present disclosure.FIG.2illustrates a schematic structural diagram of an exemplary holographic three-dimensional display device using a spatial light modulator according to various embodiments of the present disclosure.

As shown inFIGS.1-2, an exemplary spatial light modulator200of the present disclosure may include a first liquid crystal panel1for adjusting the phase of the first light L1. The first liquid crystal panel1may include a first liquid crystal layer11. The spatial light modulator200may also include a second liquid crystal panel2configured to adjust the amplitude of the first light L1. The second liquid crystal panel2may be located on one side of the first liquid crystal panel1. The second liquid crystal panel2may include a second liquid crystal layer21, and the second liquid crystal layer21may include second liquid crystal molecules211having a liquid crystal optical axis. Further, the spatial light modulator200may include a quarter-wave plate3located on the side of the second liquid crystal panel2facing away from the first liquid crystal panel1; and a polarizer4located on the side of the quarter-wave plate3facing away from the first liquid crystal panel1. The second liquid crystal panel2may include a first optical axis direction, and the difference between the refractive index of the second liquid crystal molecules211in the optical axis direction of the liquid crystal and the refractive index perpendicular to the optical axis direction of the liquid crystal may be Δn, the thickness of the second liquid crystal layer21may be d, the wavelength of the first light L1may be λ1, and 0.5λ1≤Δn×d≤0.75λ1.

The spatial light modulator200in the embodiment of the present disclosure may be used to adjust the phase and amplitude of the first light L1. It should be noted that the first light L1may not be a specific light of a specific wavelength, but generally refer to the light used for the light-emitting display. Considering that the spatial light modulator200of the embodiment of the present disclosure may be used in the holographic three-dimensional display device10, the first light L1may include, but is not limited to, red light with a wavelength of 470 nm, green light with a wavelength of 520 nm, and blue light with a wavelength of 630 nm.

In addition, considering that the spatial light modulator200in the embodiment of the present disclosure may be used in the holographic three-dimensional display device10, when observing the holographic three-dimensional display device10directly, the observer's viewing angle may be perpendicular to the plane where the spatial light modulator200is located, and the observer may observe the holographic three-dimensional display device10using the spatial light modulator200from the direction of the polarizer4. At this time, the vertical direction of the observer's viewing angle may be a first reference direction Y, and the horizontal direction may be a second reference direction X. For ease of explanation, in the embodiments of the present disclosure, among the polarization direction, alignment direction and optical axis direction mentioned, the clockwise rotation and counterclockwise rotation may be based on the viewing angle of the observer.

In the incident direction of the first light L1, the first liquid crystal panel1, the second liquid crystal panel2, the quarter-wave plate3and the polarizer4may be arranged in sequence. The first light L1may sequentially transmit through the first liquid crystal panel1, the second liquid crystal panel2, the quarter wave plate3and the polarizer4. The first light L1emitted from the polarizer4may be used for the display light emission.

The phase of the first light L1may be shifted after passing through the first liquid crystal layer11, and the amplitude of the first light L1may be changed after passing through the second liquid crystal layer21. At this time, the first light L1may be regarded as having polarized light components with different phases and amplitudes in two orthogonal directions. When passing through the quarter-wave plate3, both polarized light components may be deflected in the polarization direction. When passing through the polarizer4, the polarization direction of the transmitted light may be same as the polarization direction D4of the polarizer4, and may be used to display light emission. By adjusting the voltage difference between the electrodes on both sides of the second liquid crystal panel2, the components of the first light L1in two orthogonal directions may exhibit different phase differences, thereby adjusting the polarization direction of the first light L1. At the same time, to balance the phase difference introduced by the second liquid crystal panel2, the voltage difference between the electrodes on both sides of the first liquid crystal panel1may also be adaptively adjusted relative to the voltage difference between the electrodes on both sides of the second liquid crystal panel2.

In the embodiment of the present disclosure, the transmittance of the first light L1through the polarizer4may be used to represent the exiting brightness of the first light L1. When the transmittance is 0%, it may mean that the display device is at a state of zero brightness. When the transmittance is 100%, it may mean that the display device is at full brightness. When the electrodes on both sides of the second liquid crystal panel2are at different voltage differences, the transmittance of the first light L1through the polarizer4may be affected, accordingly, compared with when the quarter-wave plate3is not provided, the brightness of the first light L1emitted from the polarizer4after passing through the polarizer4may be affected by the quarter-wave plate3and the polarizer4. To allow the display device to display normally, the minimum brightness of the first light L1emitted from the polarizer4may need to reach 0%, and the highest brightness may need to reach 50%.

For the first light L1being red light with a wavelength of 470 nm, green light with a wavelength of 520 nm and blue light with a wavelength of 630 nm respectively, and Δn×d being different times of the wavelength λ1, different voltage differences may be respectively applied to the second liquid crystal layer21such that the first light L1may exhibit different phase differences in the optical axis direction of the liquid crystal molecules and in the direction perpendicular to the optical axis of the liquid crystal molecules. The transmittance of the first light L1after it exits the polarizer4may be detected, and the curve of the transmittance of different lights and the phase delay generated by the second liquid crystal panel2may be plotted.

FIG.3is an exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.FIG.4is an exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.FIG.5is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.FIG.6is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.FIG.7is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.

As shown inFIG.3, when Δn×d=0.5λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 50%, the holographic three-dimensional display device10may be capable of displaying light emission.

As shown inFIG.4, when Δn×d=0.5625λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 60%, the holographic three-dimensional display device10may be capable of displaying light emission.

As shown inFIG.5, when Δn×d=0.625λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 80%, the holographic three-dimensional display device10may be capable of displaying light emission.

As shown inFIG.6, when Δn×d=0.6875λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 90%, the holographic three-dimensional display device10may be capable of displaying light emission.

As shown inFIG.7, when Δn×d=0.75λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 100%, the holographic three-dimensional display device10may be capable of displaying light emission.

Therefore, when 0.5λ1≤Δn×d≤0.75λ1, the holographic three-dimensional display device10using the spatial light modulator200of the embodiment of the present disclosure may display normally.

When external ambient light enters the spatial light modulator200of the embodiment of the present disclosure from the polarizer4, the ambient light becomes polarized light. After the ambient light passes through the quarter-wave plate3, the polarization direction of the ambient light may be rotated. After the ambient light is reflected by the second liquid crystal panel2, it may pass through the quarter-wave plate3again, and the polarization direction of the ambient light may be rotated again, thus intersecting with the polarization direction D4of the polarizer4, reducing the amount of ambient light in the polarizer4. Accordingly, the crosstalk of ambient light to the first light L1may be reduced, and the display effect of the holographic three-dimensional display device10using the spatial light modulator200of the embodiment of the present application may be improved.

In some embodiments, when 0.625λ1≤Δn×d≤0.7λ1, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 80%, the holographic three-dimensional display device10using the spatial light modulator200of the embodiment of the present disclosure may have desired display effects.

When 0.625λ1>Δn×d, the maximum transmittance of red light may be significantly lower than that of green light and blue light. Therefore, although the holographic three-dimensional display device10using the spatial light modulator200of the embodiment of the present application may display normally, the display effect may be affected to a certain extent.

When 0.7λ1<Δn×d, the minimum transmittance of red light, green light and blue light may reach 0%, and the maximum transmittance of red light, green light and blue light may reach 100%, but when the second liquid crystal layer21is under different voltage differences, the transmittance of blue light changes for more than one period. Therefore, when the phase difference of the first light L1in the second liquid crystal layer21changes, the transmittance of blue light may be changed significantly, which may be not conducive to the precise control of the transmission of blue light.

FIG.8is a schematic diagram of the first alignment direction, the second alignment direction, the third alignment direction and the fourth alignment direction. In some embodiments, as shown inFIG.8andFIG.1, the first liquid crystal panel1may further include a first alignment film12with a first alignment direction D12and a second alignment film13with a second alignment direction D13. The first alignment film12and the second alignment film13may be respectively located on both sides of the first liquid crystal layer11. The second alignment direction D13may be parallel to the first reference direction Y. The second liquid crystal panel2may also include a third alignment layer22having a third alignment direction D22and a fourth alignment film23having a fourth alignment direction D23. The fourth alignment film23may be located on the side of the third alignment film22facing away from the second alignment film13. The angle between the second alignment direction D13and the fourth alignment direction D23may be approximately 45°.

Considering that the spatial light modulator200of the embodiment of the present disclosure may be used in the holographic three-dimensional display device10, when the holographic three-dimensional display device10is viewed from the front, the vertical direction of the observer's viewing angle may be the first reference direction Y.

The first alignment film12and the second alignment film13may be used to limit the rotation direction of the liquid crystal molecules in the first liquid crystal layer11such that the rotation direction of the liquid crystal molecules may gradually change along the thickness direction of the first liquid crystal layer11to adjust the phase of the first light L1. The third alignment film22and the fourth alignment film23may be used to limit the rotation direction of the liquid crystal molecules in the second liquid crystal layer21. To allow the light emitted from the first liquid crystal panel1to enter the second liquid crystal panel2, the second alignment direction D13and the third alignment direction D22may need to be parallel, and the angle between the second alignment direction D13and the fourth alignment direction D23may be approximately 45°. Therefore, the angle between the third alignment direction D22and the fourth alignment direction D23may be approximately 45° such that, along the thickness direction of the second liquid crystal layer21, the rotation direction of the liquid crystal molecules may gradually change to achieve the purpose of adjusting the amplitude of the first light L1. The angle between the first alignment direction D12and the second alignment direction D13may not be limited, for example, it may be approximately 45°.

FIG.9is an exemplary schematic diagram of the second alignment direction, the fourth alignment direction, the optical axis direction of the quarter-wave plate and the polarization direction of the polarizer according to various disclosed embodiments of the present disclosure.FIG.10is another exemplary schematic diagram of the second alignment direction, the fourth alignment direction, the optical axis direction of the quarter-wave plate, and the polarization direction of the polarizer according to various disclosed embodiments of the present disclosure.

In some embodiments, as shown inFIG.9andFIG.10, the angle between the optical axis direction D3of the quarter-wave plate and the polarization direction D4of the polarizer4may be approximately 45°.

When external ambient light enters the spatial light modulator200of the embodiment of the present application from the polarizer4, the ambient light may become polarized light. After the ambient light passes through the quarter-wave plate3, the polarization direction of the ambient light may be rotated approximately 45°. After the ambient light is reflected by the second liquid crystal panel2, it may pass through the quarter-wave plate3again, and the polarization direction of the ambient light may be rotated 45° again, thus being perpendicular to the polarization direction D4of the polarizer4. Accordingly, the transmittance of the ambient light at the polarizer4may approach approximately 0%, thereby greatly reducing the crosstalk of the ambient light to the first light L1, and significantly improving the display performance of the holographic three-dimensional display device10using the spatial light modulator200.

In some embodiments, the first liquid crystal panel1may further include a first alignment film12with a first alignment direction D12and a second alignment film13with a second alignment direction D13. The first alignment film12and the second alignment film13may be respectively located on both sides of the first liquid crystal layer11. The second alignment direction D13may be parallel to the first reference direction Y. The angle between the optical axis direction D3of the quarter-wave plate3and the second alignment direction D13may be approximately 30°, and the angle between the polarization direction D4of the polarizer4and the second alignment direction D13may be approximately 15°.

The angle between the optical axis direction D3of the quarter-wave plate3and the second alignment direction D13may be approximately 30°, and the angle between the polarization direction D4of the polarizer4and the second alignment direction D13may be approximately 15°, which may make the spatial light modulator200, on the basis of improving the display effect of the holographic three-dimensional display device10, reduce the crosstalk of the ambient light to the first light L1. Considering that the angle between the optical axis direction D3of the quarter-wave plate3and the polarization direction D4of the polarizer4may be approximately 45°, the optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 30° clockwise relative to the second alignment direction D13, and the polarization direction D4of the polarizer4may be regarded as being rotated 15° clockwise relative to the optical axis direction D3of the quarter-wave plate3. At the same time, the polarization direction D4of the polarizer4may be regarded as being rotated 45° clockwise relative to the second alignment direction D13. Alternatively, the optical axis direction D3of the quarter-wave plate may be regarded as being rotated counterclockwise by 30° relative to the second alignment direction D13, and the polarization direction D4of the polarizer4may be regarded as being rotated counterclockwise by 15° relative to the optical axis D3of the quarter-wave plate3. At the same time, the polarization direction D4of the polarizer4may be regarded as being rotated counterclockwise by 45° relative to the second alignment direction D13.

In some embodiments, the central wavelength range of the quarter-wave plate3may be in a range of approximately 495 nm-605 nm.

The quarter-wave plate3may rotate the polarization direction of the first light L1. When the wavelength of the light is within the central wavelength range of the quarter-wave plate3, the rotation angles of the polarization directions of light of different wavelengths may be basically the same. At this time, the quarter-wave plate3may affect the brightness of the light of different wavelengths (colors) to the same degree, which may reduce the display color difference of the holographic three-dimensional display device10using the spatial light modulator200.

In some embodiments, the wavelength λ1 of the first light L1may satisfy 495 nm-Δλ≤λ1≤605 nm+Δλ. Δλ may be the first wavelength deviation.

When the wavelength of the light is outside the central wavelength range of the quarter-wave plate3, if the difference between the wavelength of the light and the upper or lower limit of the central wavelength range is within the allowable range, the rotation angle of the polarization direction of the light may also be considered, as well as the rotation angle of the polarization direction of the light whose wavelength is within the central wavelength range of the quarter-wave plate3, may have no much difference. Accordingly, the holographic three-dimensional display device10using the spatial light modulator200may have obvious color difference.

For example, Δλ=25 nm, the first light L1may be red light with a wavelength of 470 nm, green light with a wavelength of 520 nm, and blue light with a wavelength of 630 nm. The green light with a wavelength of 520 nm is located within the central wavelength range of the quarter-wave plate3, the difference between the red light with a wavelength of 470 nm and the lower limit 495 nm of the central wavelength range of the quarter-wave plate3may be 25 nm, and the difference between the blue light of a wavelength of 630 nm and the upper limit 605 nm of the central wavelength range of the quarter-wave plate3may be 25 nm, it may be considered that the quarter-wave plate3may affect the brightness of light of different wavelengths (colors) to the same degree, which may reduce the problem of display color difference of the holographic three-dimensional display device10using the spatial light modulator200.

It should be noted that when the holographic three-dimensional display device10using the spatial light modulator200emits light, different pixels may use different colors of light and may correspond to different wavelengths. When determining the central wavelength range of the quarter-wave plate3, the wavelengths of different light may be located within the central wavelength range as much as possible. If the central wavelength range of the quarter-wave plate3is difficult to cover the wavelengths of all different lights, for wavelengths located outside of the central wavelength range of the quarter-wave plate3, the difference between the wavelength of light outside the central wavelength range of the quarter-wave plate3and the upper or lower limit of the central wavelength range of the quarter-wave plate3should be as small as possible.

FIG.11is a schematic structural diagram of another exemplary spatial light modulator according to various disclosed embodiments of the present disclosure. In some embodiments, as shown inFIG.11, the spatial light modulator200may also include a half-wave plate5. The half-wave plate5may be disposed on the quarter-wave plate3and the polarizer4.

After the first light L1is emitted from the second liquid crystal panel2, it may pass through the quarter-wave plate3, and the polarization direction of the first light L1may be rotated. After passing through the half-wave plate5, the polarization direction of the first light L1may be rotated again and then emitted from the polarizer4. When the holographic three-dimensional display device10using the spatial light modulator200uses red light with a wavelength of 470 nm, green light with a wavelength of 520 nm, and blue light with a wavelength of 630 nm to display light emission, the wavelength of the red light and the blue light may be both outside the central wavelength range of the quarter-wave plate3. After setting the half-wave plate5, the red light and blue light may be reversely compensated to further reduce the influence of the quarter-wave plate3on the brightness of red light and blue light to further reduce the display chromatic aberration of the holographic three-dimensional display device10.

It should be noted that, similar to the quarter-wave plate3, the central wavelength range of the half-wave plate5may also be approximately 495 nm-605 nm.

FIG.12is an exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.13is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.14is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.15is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.16is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.17is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.

In some embodiments, as shown inFIGS.12-17, the angle between the optical axis direction D3of the quarter-wave plate3and the polarization direction D4of the polarizer4may be approximately 15°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may be approximately 75°.

In one embodiment of the present disclosure, the polarization direction D4of the polarizer4may not be limited. For example, the angle between the polarization direction D4of the polarizer4and the second alignment direction D13may be 0°, 45° or 90°, for example, the integer time of 45°. After the ambient light passes through the half-wave plate5and the quarter-wave plate3, it may be reflected at the second liquid crystal panel2and pass through the quarter-wave plate3and the half-wave plate5again. When the angle between the polarization direction D4of the polarizer4and the second alignment direction D13is an integer time of 45°, it may be convenient to set the optical axis direction D3of the quarter-wave plate3and the optical axis direction D5of the half-wave plate5such that the polarization direction of the ambient light after the reflection may be perpendicular to the polarization direction D4of the polarizer4, thereby reducing the crosstalk of the ambient light to the first light L1.

The optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 15° clockwise with respect to the polarization direction D4of the polarizer4, and the optical axis direction D5of the half-wave plate5may be regarded as being rotated 75° clockwise with respect to the polarization direction D4of the polarizer4. Alternatively, the optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 15° counterclockwise relative to the polarization direction D4of the relative polarizer4, and the optical axis direction D5of the half-wave plate5may be regarded as being rotated 75° counterclockwise relative to the polarization direction D4of the polarizer4.

For example, Δn×d=0.75λ1, and the polarization direction D4of the polarizer4may be rotated clockwise by 0°, 45°, 90° or 135° relative to the second alignment direction D13, and the optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 15° clockwise relative to the polarization direction D4of the polarizer4, and the optical axis direction D5of the half-wave plate5may be regarded as being rotated 75° clockwise relative to the polarization direction D4of the polarizer4. In the above four examples, when the first light L1produces different phase differences in the second liquid crystal layer21, the transmittance of the lights of different colors after exiting the polarizer4may be detected and corresponding curves may be plotted. The curves of the four examples may be basically the same. For example, the minimum transmittance of red light, green light and blue light may be able to reach 0%, and the maximum transmittance of red light, green light and blue light may be able to reach 100%. Thus, the holographic three-dimensional display device10may display light emission.

In some embodiments, referring toFIGS.12-17, the angle between the optical axis direction D3of the quarter-wave plate3and the polarization direction D4of the polarizer4may be approximately 75°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may be approximately 75°.

Similarly, the optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 75° clockwise relative to the polarization direction D4of the polarizer4, and the optical axis direction D5of the half-wave plate5may be regarded as being rotated 15° clockwise relative the polarization direction D4of the polarizer4. Alternatively, the optical axis direction D3of the quarter-wave plate3may be regarded as being rotated 75° counterclockwise relative to the polarization direction D4of the relative polarizer4, and the optical axis direction D5of the half-wave plate5may be regarded as being rotated 15° counterclockwise relative to the polarization direction D4of the relative polarizer4. Accordingly, the minimum transmittance and maximum transmittance of red light, green light and blue light may enable the holographic three-dimensional display device10to display light emission.

FIG.18is a schematic structural diagram of another exemplary spatial light modulator according to various embodiments of the present disclosure. As shown inFIG.18, In some embodiments, the spatial light modulator200may also include a first color resistor layer61disposed between the first liquid crystal panel1and the second liquid crystal panel2, a connection layer62disposed between the first color resistor layer61and the second liquid crystal panel2; and a second color resistor layer63disposed between the connection layer62and the second liquid crystal panel2.

The first color resistor layer61and the second color resistor layer63may be used to reduce crosstalk between lights of different colors and at the same time to reduce the possibility of external ambient light transmitting through the second liquid crystal panel2. The connection layer62may be configured to connect the first color resistor layer61and the second color resistor layer63such that they may form an integral body.

The present disclosure also provides a holographic three-dimensional display device.FIG.19is a structural diagram of an exemplary holographic three-dimensional display device according to various disclosed embodiments of the present disclosure. As shown inFIG.19, a holographic three-dimensional display device10may include a light source module100for emitting coherent light in a timed sequence; and a beam expansion and collimation module located on the light-exiting side of the light source module100. The beam expansion and collimation module may be configured to expand and collimate the light emitted from the light source module100. The holographic three-dimensional display device10may also include a spatial light modulator200. The spatial light modulator200may be a present disclosed spatial light modulator described above. The spatial light modulator200may be located on a side of the beam expansion and collimation module away from the light source module100. Further, the holographic three-dimensional display device may include a field lens module300located on the side of the spatial light modulator200away from the light source module100, and a liquid crystal grating module400used to direct the light emitted by the field lens module300toward the positive direction or the negative direction of the second reference direction X. The second reference direction X may be perpendicular to the first reference direction Y.

It should be emphasized that when observing the holographic three-dimensional display device10from the normal direction, the observer's viewing angle may be perpendicular to the plane where the spatial light modulator200is located, and the observer may observe the holographic three-dimensional display device10including the spatial light modulator200from the direction of the polarizer4. At this time, the vertical direction of the observer's viewing angle may be the first reference direction Y, and the horizontal direction may be the second reference direction X. For example, the positive direction of the second reference direction X may be the left side of the observer, and the negative direction of the second reference direction X may be the right side of the observer. In addition, in the polarization direction, the alignment direction and the optical axis direction, clockwise rotation and counterclockwise rotation may be based on the observer's perspective.

The light source module100may be configured to emit coherent light in a timed manner. The emitted light may include two components in orthogonal directions, and the phase difference between the two components may remain consistent. The beam expansion and collimation module may be configured to expand and collimate the light emitted from the light source module100such that coherent light may be incident into the spatial light modulator200in parallel. After the adjustment by the spatial light modulator200, the coherent light may form polarized light, and the brightness may be adjusted by the second liquid crystal panel2of the spatial light modulator200. The field lens module300and the liquid crystal grating module400may be configured to bend the polarized light along the second reference direction X such that there may be a certain difference in the images seen by the observer's eyes, thereby presenting a holographic three-dimensional display effect.

FIG.20is another exemplary schematic diagram of a holographic three-dimensional display device according to various disclosed embodiments of the present disclosure.FIG.21is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.22is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate and the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.23is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.

In some embodiments, as shown inFIG.20-23, the spatial light modulator200may further include a half-wave plate5disposed between the quarter-wave plate3and the polarizer4. Along clockwise of the normal viewing direction, the angle between the optical axis direction D3of the quarter-wave plate3and the polarization direction D4of the polarizer4may be approximately 75°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may approximately 15°. In other embodiments, the angle between the optical axis direction D5of the half-wave plate to the polarization direction D4of the polarizer4may be approximately 15°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may be approximately 75°. The two examples have been described previously and will not be repeated here.

In some embodiments, referring toFIGS.20-23, the light source module100may emit at least first light L1, second light L2and third light L3of different colors. The second liquid crystal panel2may also include a plurality of first electrodes24and at least one second electrode25. The plurality of first electrodes24and the second electrode25may be respectively located on both sides of the second liquid crystal layer21along its own thickness direction. When the voltage difference between the first electrode24and the second electrode25is 0V, the transmittance of the first light L1in the second liquid crystal panel2, the transmittance of the second light L2in the second liquid crystal panel2and the transmittance of the third light L3in the second liquid crystal panel2may be greater than a first reference transmittance.

For ease of explanation, in one embodiment of the present disclosure, the first light L1may be red light with a wavelength of 470 nm, the second light L2may be a green light with a wavelength of 520 nm, and the third light L3may be a blue light with a wavelength of 630 nm. The minimum transmittance of red light, green light and blue light can reach 0%, and the maximum transmittance of red light, green light and blue light can reach 80%, so the holographic three-dimensional display device10can display light. When the voltage difference between the first electrode24and the second electrode25is 0V, the phase difference of the light in the second liquid crystal layer21may be zero, and the transmittance of red light, green light and blue light may be greater than 80%. Thus, the transmittance of the first light L1on the second liquid crystal panel2, the transmittance of the second light L2on the second liquid crystal panel2, and the transmittance of the third light L3on the second liquid crystal panel2may be greater than the first reference transmittance. For example, the first reference transmittance may be approximately 80%. At this time, the holographic three-dimensional display device10may display a white image. That is to say, in the initial state, the holographic three-dimensional display device10may be at a white constant light state.

FIG.24is an exemplary schematic diagram of a portion of the holographic three-dimensional display device according to various embodiments of the present disclosure.FIG.25is another exemplary structural schematic diagram of a holographic three-dimensional display device according to various disclosed embodiments of the present disclosure.

In some embodiments, as shown inFIG.24-25, the holographic three-dimensional display device10may also include a first area AA1and a second area AA2. At least a portion of the second area AA2may be located at the positive direction side and the negative direction side of the first area AA1in the second reference direction Y. The second liquid crystal panel2may also include a first electrode24and a second electrode25. The first electrode24may include a first sub-electrode241and a second sub-electrode242. The first sub-electrode241may be located in the first area AA1, and the second sub-electrode242may be located in the second area AA2. When the holographic three-dimensional display device10displays light, the voltage difference between the first sub-electrode241and the second electrode25may be higher than the voltage difference between the second sub-electrode242and the second electrode25.

Along the second reference direction X, the second area AA2may be located at both sides of the first area AA1. The second area AA2may correspond to the left and right peripheral vision angles of the observer, and the first area AA1may correspond to the normal viewing angle of the observer. In the two aforementioned embodiments, when Δn×d=0.625λ1, and when the light corresponds to different phase differences in the second liquid crystal layer21, the transmittance of the lights of different colors after exiting the polarizer4may be detected, and a curve may be plotted. The voltage difference between the first electrode24and the second electrode25may gradually increase, and the phase difference of the light in the second liquid crystal layer21may be inversely proportional to the transmittance. Therefore, the voltage difference between the first sub-electrode241and the second electrode25may be higher than the voltage difference between the second sub-electrode242and the second electrode25, and the brightness of the second area AA2may be greater than the height of the first area AA1. Considering that the human eye may have a poor ability to perceive the peripheral vision angle, increasing the brightness of the second area AA2may make the brightness perceived by the human eye in the first area AA1and the second area AA2consistent.

FIG.26is another exemplary curve showing the transmittance of light corresponding to different phase differences in the second liquid crystal layer of the spatial light modulator according to various disclosed embodiments of the present disclosure.FIG.27is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.FIG.28is another exemplary schematic diagram of the optical axis direction of the quarter-wave plate, the optical axis direction of the half-wave plate and the polarization direction of the polarizer.

In some embodiments, as shown inFIGS.26-28, and in conjunction withFIG.20, the spatial light modulator200may also include a half-wave plate5disposed between the quarter-wave plate3and the polarizer4. Along the counterclockwise direction from the normal view direction, the angle between the optical axis direction D3of the quarter-wave plate3and the polarization direction D4of the polarizer4may be approximately 75°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may be approximately 15°. In other embodiments, along the counterclockwise direction from the normal view direction, the angle between the optical axis direction D3of the quarter-wave plate D3and the polarization direction D4of the polarizer4may be approximately 15°, and the angle between the optical axis direction D5of the half-wave plate5and the polarization direction D4of the polarizer4may be approximately 15°. The two examples have been described previously and will not be repeated here.

In some embodiments, continuing to refer toFIGS.26-28and in conjunction withFIG.20, the light source module100may emit at least the first light L1, the second light L2and the third light L3of different colors. The second liquid crystal panel2may also include a plurality of first electrodes24and at least one second electrode25respectively located on both sides of the second liquid crystal layer21along its thickness direction. When the voltage difference is 0V, the transmittance of the first light L1through the second liquid crystal panel2, the transmittance of the second light L2through the second liquid crystal panel2and the transmittance of the third light L3through the second liquid crystal panel2may be less than the second reference transmittance.

For ease of explanation, in the embodiment of the present disclosure, the first light L1may be red light with a wavelength of 470 nm, the second light L2may be a green light with a wavelength of 520 nm, and the third light L3may be a blue light with a wavelength of 630 nm. When Δn×d=0.625λ1, and when the light corresponds to different phase differences, the transmittance of the lights of different colors after emitting from the polarizer4may be measured and a curve may be plotted. The curves of the previous two embodiments may be consistent. The minimum transmittance of red light, green light and blue light may reach 20%, and the maximum transmittance of red light, green light and blue light may reach 100%. Accordingly, the holographic three-dimensional display device10may display light. When the voltage difference between the first electrode24and the second electrode25is 0V, the phase difference of the light in the second liquid crystal layer21is zero, and the transmittance of red light, green light and blue light is less than 20%. Thus, the transmittance of the first light L1on the second liquid crystal panel2, the transmittance of the second light L2on the second liquid crystal panel2, and the transmittance of the third light L3on the second liquid crystal panel2may be less than a second reference transmittance. In one embodiment, the second reference transmittance may be 20%. At this time, the holographic three-dimensional display device10may display a black image. That is to say, in the initial state, the holographic three-dimensional display device10may be in a black and normally dark state.

In some embodiments, continuing to refer toFIGS.24-25, the holographic three-dimensional display device10may also include a first area AA1and a second area AA2. At least a portion of the second area AA2may be located at the positive direction side and the negative direction side of the first area AA1along the second reference direction X. The second liquid crystal panel2may also include a first electrode4and a second electrode25. The first electrode24may include a first substrate electrode241. The first sub-electrode241may be located in the first area AA1, and the second sub-electrode242may be located in the second area AA2. When the holographic three-dimensional display device10displays light, the voltage difference between the first sub-electrode241and the second electrode25may be lower than the voltage difference between the second sub-electrode241and the second electrode25.

Along the second reference direction X, the second area AA2may be located at the two sides of the first arear AA1. The second area AA2may correspond to the peripheral viewing angles of the left and right sides of the viewer, and the first area AA1may correspond to the normal viewing angle of viewer. In the two aforementioned embodiments, when Δn×d=0.625λ1 and when the light corresponds to different phase differences in the second liquid crystal layer21, the transmittance of the lights of different colors after exiting the polarizer4may be measured and curves may be plotted. The voltage difference between the first electrode24and the second electrode25may gradually increase, and the phase difference of the light in the second liquid crystal layer21may be proportional to the transmittance. Therefore, the voltage difference between the first sub-electrode241and the second electrode25may be lower than the voltage difference between the second sub-electrode242and the second electrode25. Thus, the brightness of the second area AA2may be higher than the brightness of the first area AA1. Considering that the human eye may have a poor ability to perceive the peripheral vision angle, increasing the brightness of the second area AA2may make the brightness perceived by the human eye in the first area AA1and the second area AA2consistent.

Thus, the present disclosure provides a spatial light modulator200and a holographic three-dimensional display device10. The first liquid crystal panel1may be configured to adjust the phase of the first light L1, and the second liquid crystal panel2may be configured to adjust the amplitude of the first light L1. The quarter-wave plate3may be located on the side of the second liquid crystal panel2facing away from the first liquid crystal panel1, and the polarizer4may be located on the side of the quarter-wave plate3facing away from the first liquid crystal panel1. The first light L1may pass through the first liquid crystal panel1, the second liquid crystal panel2, the quarter-wave plate3and the polarizer4in sequence, and may be emitted from the spatial light modulator200. The external light may be formed into a polarized light after passing through the polarizer4. After passing through the quarter-wave plate3, the polarization direction may be rotated. After being reflected at the second liquid crystal panel2, the polarization direction may be changed again after passing through the quarter-wave plate3and may be perpendicular to the polarization direction D4of the polarizer4, and may be difficult to transmit through the polarizer4. Thus, the impact of external light reflected on the second liquid crystal panel2on the exiting light may be reduced. The difference between the refractive index of the second liquid crystal molecules211along the optical axis of the liquid crystal and the refractive index perpendicular to the optical axis of the liquid crystal may be Δn, the thickness of the second liquid crystal layer21may be d, the wavelength of the first light L1may be λ1, and 0.5λ1≤Δn×d≤0.75λ1. When the second liquid crystal panel2adjusts the first light L1, on the premise that the minimum brightness of the first light L1may not be changed much, the maximum brightness of the first light L1may be increased; and the display effect of the holographic three-dimensional display device10may be enhanced.

To sum up, the present disclosure provides a spatial light modulator and a holographic three-dimensional display device, in which the first liquid crystal panel may be used to adjust the phase of the first light, and the second liquid crystal panel may be configured to adjust the amplitude of the first light. The quarter-wave plate may be located on a side of the second liquid crystal panel facing away from the first liquid crystal panel, and the polarizer may be located on a side of the quarter-wave plate facing away from the first liquid crystal panel. The first light may pass through the first liquid crystal panel, the second liquid crystal panel, the quarter-wave plate and the polarizer in sequence, and then emit from the spatial light modulator. The external light may be formed into polarized light after passing through the polarizer. After passing through the quarter-wave plate, the polarization direction may be rotated. After being reflected at the second liquid crystal panel, the polarization direction may be rotated again after passing through the quarter-wave plate. The polarization direction of the polarizer may be vertical, making it difficult to transmit through the polarizer, which may reduce the impact of external light reflected on the second liquid crystal panel on the exiting light. The difference between the refractive index of the second liquid crystal molecules along the optical axis of the liquid crystal and the refractive index perpendicular to the optical axis of the liquid crystal may be Δn, the thickness of the second liquid crystal layer may be d, the wavelength of the first light may be λ1, and 0.5λ1≤Δn×d≤0.75λ1. When the second liquid crystal panel adjusts the first light, the maximum brightness of the first light may be increased while keeping the minimum brightness of the first light unchanged. Thus, the display effect of the holographic three-dimensional display device may be improved.

The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person familiar with the technical field can easily think of various equivalent methods within the technical scope disclosed in the present disclosure. Modification or replacement replacements shall be covered by the protection scope of this disclosure. Therefore, the protection scope of this disclosure should be subject to the protection scope of the claims.