CN112255820A - Naked eye three-dimensional display device - Google Patents
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- G02B30/20—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images by providing first and second parallax images to an observer's left and right eyes
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Abstract
The invention provides a naked eye three-dimensional display device, which comprises: a display section including a display cell array in which a plurality of display cell arrays are arranged; the visual angle regulating device comprises a harmonic diffraction lens array formed by arranging a plurality of harmonic diffraction lens sub-unit arrays, wherein each harmonic diffraction lens sub-unit corresponds to one display unit, the harmonic diffraction lens sub-units of the harmonic diffraction lens array are divided into a plurality of groups, light rays emitted by the same group of harmonic diffraction lens sub-units can be converged into the same viewpoint, and light rays emitted by different groups of harmonic diffraction lens sub-units can be converged into different viewpoints. Therefore, different three-dimensional display effects observed at different viewing angles can be realized, and the utilization efficiency of light can be improved.
Description
Technical Field
The invention relates to the technical field of three-dimensional display, in particular to a naked eye three-dimensional display device.
Background
As one of the main sources of information acquired by human, vision is very important in daily life. Unlike natural scenes, conventional display devices can only present two-dimensional images at present. This lack of depth-based flat information limits human exploration and cognition in the world to some extent. Studies have shown that almost 50% of the human brain is used to participate in the processing of visual information, and the presentation of two-dimensional images results in a reduction in brain utilization. The naked eye 3D (3D) display has great application value in movie and television, games, education, vehicle-mounted, aviation, medical treatment and military. Taking the military field as an example, the visualization of a 3D image is required in each link of machine manufacturing, battlefield analysis, military command, remote operation, and the like, and the improvement of the working efficiency will be greatly influenced. Therefore, 3D display is known as "next generation display technology", and is one of the techniques in which important research fields and many display companies are controversial.
Based on the mechanism and method for realizing naked eye 3D display of parallax barrier, cylindrical lens array, space-time multiplexing or integrated optical field, etc., the optical element with periodic microstructure or nano structure is used to regulate and control the phase of the display optical field and project the image information of different visual angles to different visual angles in the mode of approximate parallel light beams. Although the autostereoscopic display technology has made great progress, the naked-eye 3D display technology has not yet succeeded in entering the field of flat panel display. The display problems of dizziness (convergence adjustment contradiction), image crosstalk/ghost, resolution reduction and the like, and the device structure problems of ultra-thinning, light utilization rate and the like need to be solved urgently.
Chinese patent CN 105959672B discloses an naked eye three-dimensional display device based on active light emitting display technology, and proposes that a directional phase plate including a nano-grating pixel structure is used to perform wavefront modulation on an incident image to form a multi-view 3D image. However, the pixels of the phase plate need to be perfectly attached to the pixels of the display screen, the process difficulty is high, and precise alignment is difficult to achieve.
In addition, the Chinese patent mentions a technique of precisely controlling light by using optical diffraction. As shown in fig. 1, the principle of a 3D display based on a nanograting (a type of diffractive optical element) is: the structure diagram of the diffraction grating with the structure scale at the nanometer level under the XY plane and the XZ plane. According to the grating equation, the period and the orientation angle of the diffraction grating pixel 101 satisfy the following relationship:
wherein the light is incident on the XY plane at a certain angle,
and
sequentially showing the diffraction angle of the diffracted light 202 (the angle between the diffracted light and the positive direction of the Z axis) and the azimuth angle of the diffracted light 202 (the angle between the diffracted light and the positive direction of the X axis),
and λ sequentially represent the incident angle (angle of incident ray to the positive Z-axis) and wavelength of the light source 201, Ʌ and
the period and the orientation angle (included angle between the groove-shaped direction and the positive direction of the Y axis) of the nano diffraction grating 101 are sequentially shown, and n represents the refractive index of the light wave in the medium. In other words, after the wavelength and the angle of incidence of the incident light and the diffraction angle and the diffraction azimuth angle of the diffracted light are specified, the period and the orientation angle of the nano-grating can be calculated by the above two formulas. For example, 650 nm wavelength red light is incident at an angle of 60 °, the diffraction angle of the light is 10 °, the diffraction azimuth angle is 45 °, and the corresponding nano diffraction grating period is 550 nm and the orientation angle is-5.96 ° by calculation.
However, the theoretical diffraction efficiency of the two-step nano-grating in this technique is about 40%. The light utilization rate is a very important measure for the display device, and a method for improving the diffraction efficiency needs to be fully considered.
The diffraction efficiency of the nano-grating is related to the number of steps, and in order to calculate the efficiency of the nano-grating, the far-field diffraction condition of the nano-grating needs to be determined. As shown in fig. 2, there are multiple steps in one DOE (Diffractive Optical Element) period, each step corresponds to one sub-period, and the periodic transmittance function of the DOE can be expressed as the sum of the sub-transmittance functions of all the steps. Assuming that the period is T and the DOE has N steps, the width of the sub-period is a rectangular function of T/N, and the central position is
Where l is the sub-cycle number, the phase delay of a sub-cycle can be expressed as
The total phase delay is
。
Diffraction efficiency is generally defined as the ratio of the energy of a beam of light diffracted in the m-th order to the total incident light energy after passing through the structure of the diffractive element. One centered at x, having a period width of T, a sub-period width of T/N, and a sub-period phase delay
Total phase delay of
The fraunhofer far-field diffraction profile of the sub-periodic structure can be expressed as:
the fraunhofer far-field diffraction distribution of the DOE period can be represented by the superposition of the far-field diffraction of N sub-periods:
for the whole DOE, the structure corresponds to an infinite number of period repetitions, only if, due to interference effects
The non-zero light intensity appears, m is the order, and the far-field diffraction amplitude of the mth order is obtained by the formula:
efficiency of m order
Can be represented as AmAm*：
Wherein:
the diffraction efficiency is obtained in conclusion
The expression is as follows:
generally when a DOE is used, the first diffraction order is of concern, as can be seen from the above equation, when
When the unit is wavelength, the diffraction efficiency of the first order reaches a maximum value, and the corresponding height d = λ/(n-1) of the phase structure. Thus, when m = 1, the diffraction efficiency can be expressed as:
the efficiency of the diffraction element corresponds to the number of steps as follows:
| DOE |
2 | 4 | 8 | 16 | 32 |
| Diffraction efficiency (%) | 40.53 | 81.06 | 94.96 | 98.72 | 99.68 |
When the gray scale lithography process is used, the continuous surface type can be considered as N → ∞ (in this case, the step grating can be regarded as a blazed grating, or a blazed grating is a special form in which the step number N → ∞ of the step grating is approximated), and the diffraction efficiency expression of the DOE is:
from the above equation, it can be easily seen that the diffraction efficiency is maximized when the phase retardation is the same as the diffraction order. Phase delay
Can be expressed as:
the formula for diffraction efficiency can therefore also be written as:
the models selected in the derivation are all the derivation from medium to air, and the central wavelength lambda is assumed0532nm was chosen, taking into account the dispersion of the material over the wavelength, BK7 (a common borosilicate crown glass) was used as the medium, and the refractive index was fitted with the schott dispersion formula. The diffraction efficiency curves after passing through the DOE for incident light of different wavelengths are as shown in fig. 3.
Therefore, there is a need for an improved solution to overcome the above problems.
Disclosure of Invention
The invention aims to provide a naked eye three-dimensional display device which not only can realize different three-dimensional display effects observed under different visual angles, but also can improve the utilization efficiency of light.
To achieve the object, according to one aspect of the present invention, there is provided a naked eye three-dimensional display device including: a display section including a display cell array in which a plurality of display cell arrays are arranged; the visual angle regulating device comprises a harmonic diffraction lens array formed by arranging a plurality of harmonic diffraction lens sub-unit arrays, wherein each harmonic diffraction lens sub-unit corresponds to one display unit, the harmonic diffraction lens sub-units of the harmonic diffraction lens array are divided into a plurality of groups, light rays emitted by the same group of harmonic diffraction lens sub-units can be converged into the same viewpoint, and light rays emitted by different groups of harmonic diffraction lens sub-units can be converged into different viewpoints.
Compared with the prior art, the harmonic diffraction lens array formed by arranging the plurality of harmonic diffraction lens sub-unit arrays is used for displaying the three-dimensional image, so that different three-dimensional display effects observed under different viewing angles can be realized, and the utilization efficiency of light can be improved.
Drawings
FIG. 1 is a schematic diagram of a 3D display principle based on a nano-grating in the prior art;
FIG. 2 is a schematic side view of the nano-grating of FIG. 1;
FIG. 3 is a graph showing the relationship between diffraction efficiency and step data of the nano-grating of FIG. 1;
FIG. 4 is a schematic structural diagram of a naked eye three-dimensional display device in one embodiment of the invention;
FIG. 5 is a schematic diagram of the design of a harmonic diffractive lens array in accordance with the present invention;
FIG. 6 is an exemplary diagram of a harmonic diffractive lens array formed based on the design principles shown in FIG. 5 in the present invention;
FIG. 7 is a schematic structural diagram of a harmonic diffraction element used in the viewing angle modulator of the present invention;
FIG. 8 is a graph of the diffraction efficiency of a harmonic diffraction element with a central wavelength of 632 nm;
FIG. 9 is a graph of the diffraction efficiency of a harmonic diffraction element with a center wavelength of 700 nm;
FIG. 10 is a graph of the fractional-band diffraction efficiency of a harmonic diffraction element centered at 700 nm;
FIG. 11 is a view of a parabolic surface;
FIG. 12 is a schematic of quadric collapse;
FIG. 13 is a schematic diagram of a radius formula for a diffractive element and a harmonic diffractive element;
FIG. 14 is a schematic of collapse calculation;
FIG. 15 is a schematic diagram of a harmonic diffractive lens structure.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description of the embodiments, structures, features and effects according to the present invention will be given with reference to the accompanying drawings and preferred embodiments.
The invention provides a naked eye three-dimensional display device which can realize different three-dimensional display effects viewed at different visual angles, improve the utilization efficiency of light, eliminate chromatic dispersion and realize better color display.
Fig. 4 is a schematic structural diagram of a naked eye three-dimensional display device in an embodiment of the invention. As shown in fig. 4, the naked eye three-dimensional display device 400 includes a display part 410 and a viewing angle adjusting device 420.
The display component 410 may also be referred to as a display screen, and the display component may be an OLED screen, a miniLED screen, an OLED screen, or a micro led screen, and may also be an LCD display screen, etc. Preferably, the display part 410 is a micro light emitting diode (micro led) display screen, each of the light emitting diodes has a length and a width of 100 micrometers or less, and each of the light emitting diodes can be driven to light individually. Due to the adoption of the micro led screen, the resolution of the display part 410 can be greatly improved, thereby improving the resolution of the final 3D display image. The display part 410 includes a display unit array in which a plurality of display units 411 are arrayed. Only eight display units 411 are shown in fig. 4, and in practice, the number of the display units 411 may be many. In one embodiment, the display unit is a display pixel, or may be a plurality of display pixels, and the display pixels are LED pixels or LCD pixels. The display unit can be one or several pixels in the display screen of the electronic product, and the content displayed by the LED pixels or the LCD pixels can be refreshed and changed.
The viewing angle adjusting device 420 includes a harmonic diffractive lens array formed by a plurality of harmonic diffractive lens sub-units 421 arranged in an array. Each harmonic diffractive lens sub-unit 421 corresponds to one display unit 411. The harmonic diffraction lens subunits 421 of the harmonic diffraction lens array are divided into a plurality of groups, the same group of harmonic diffraction lens subunits have a common focus, and the light rays emitted by the harmonic diffraction lens subunits converge into a same viewpoint; different sets of harmonic diffractive lens sub-units have different focal points, and the light rays emitted by the harmonic diffractive lens sub-units are converged into different view points.
In an alternative embodiment, each display unit comprises at least a red pixel, a blue pixel and a green pixel, and light rays emitted by the red pixel, the blue pixel and the green pixel of each display unit are converged after passing through the same harmonic diffraction lens subunit.
In the example of FIG. 4, the harmonic diffractive lens subunits 421-1 and 421-5 are a group, the light beams emitted from both are focused to the viewpoint 1, the harmonic diffractive lens subunits 421-2 and 421-6 are a group, the light beams emitted from both are focused to the viewpoint 2, the harmonic diffractive lens subunits 421-3 and 421-7 are a group, the light beams emitted from both are focused to the viewpoint 3, and the harmonic diffractive lens subunits 421-4 and 421-8 are a group, the light beams emitted from both are focused to the viewpoint 4. Of course, fig. 4 shows only 8 harmonic diffractive lens sub-units as an example, and it is obvious that the data of the harmonic diffractive lens sub-units will be many, and may be thousands or more, and the viewpoints will be many, and may be thousands or more depending on the design.
In order to realize 3D display, the display unit corresponding to each group of harmonic diffraction lens subunits displays an image of one visual angle, and the display units corresponding to different groups of harmonic diffraction lens subunits display images of different visual angles. Thus, when the user views the display component at the first position, one eye of the user is located at the first viewpoint (e.g., viewpoint 1) and can see the light emitted by the first group of harmonic diffractive lens sub-units, and the other eye is located at the second viewpoint (e.g., viewpoint 2) and can see the light emitted by the second group of harmonic diffractive lens sub-units, so that the user can see the images with two different viewing angles having a difference in viewing angle at the first position to form the first three-dimensional image in the user's brain, when the user views the display component at the second position, one eye of the user is located at the third viewpoint (e.g., viewpoint 3) and can see the light emitted by the third group of harmonic diffractive lens sub-units, and the other eye is located at the fourth viewpoint (e.g., viewpoint 4) and can see the light emitted by the fourth group of harmonic diffractive lens sub-units, so that the user can see the images with two different viewing angles at the second position, so as to form a second three-dimensional image, wherein the first three-dimensional image and the second three-dimensional image have different visual angles, namely, the three-dimensional stereo effect seen at the first position and the second position is different, thereby realizing the real three-dimensional stereo effect of full parallax. It should be noted that the expressions first, second, third and fourth are only used for convenience of understanding, and in fact, the first viewpoint and the first position are both generally referred to as a viewpoint and a position, and it is not strictly defined where the first viewpoint and the first position are, for example, the viewpoint 4 in fig. 4 can also be referred to as the first viewpoint.
FIG. 5 is a schematic diagram of the design of a harmonic diffractive lens array in accordance with the present invention. As shown in FIG. 5, four harmonic diffractive lenses 510, 520, 530, and 540 are illustrated, each having its own focal point. In order to form the harmonic diffractive lens array of the present invention, it is necessary to divide each harmonic diffractive lens into 16 harmonic diffractive lens sub-units, four of which are labeled 1a, 1b, 1c and 1d, 2a, 2b, 2c and 2d, 3a, 3b, 3c and 3d, 4a, 4b, 4c and 4d, respectively, in each harmonic diffractive lens, then 1a, 2a, 3a and 4a are combined into one harmonic diffractive lens sub-unit assembly 550, and the remaining harmonic diffractive lens sub-units 1b, 2b, 3b and 4b, etc. are also combined into one harmonic diffractive lens sub-unit assembly. Even if the harmonic diffraction lens subunits are recombined into a harmonic diffraction lens array, the harmonic diffraction lens subunits originally belonging to the same harmonic diffraction lens still have the same focal point, and the emergent light rays still converge together.
FIG. 6 is an exemplary diagram of a harmonic diffractive lens array formed based on the design principles shown in FIG. 5 in the present invention. The harmonic diffraction lens subunits belonging to the same group are scattered and distributed at different positions, the harmonic diffraction lens subunits belonging to different groups are arranged in a staggered manner, and one harmonic diffraction lens subunit in each group of harmonic diffraction lens subunits in all groups of harmonic diffraction lens subunits is adjacent to one harmonic diffraction lens subunit in other groups of harmonic diffraction lens subunits to form a harmonic diffraction lens subunit combination. As shown in fig. 6, 1a, 2a, 3a and 4a form one harmonic diffractive lens subunit combination, 1b, 2b, 3b and 4b form another harmonic diffractive lens subunit combination, and similarly, 1c, 2c, 3c and 4c, and 1d, 2d, 3d and 4d form harmonic diffractive lens subunit combinations, respectively. Furthermore, since 1a, 1b, 1c and 1d belong to the same harmonic diffractive lens, they are divided into a set of harmonic diffractive lens sub-units, and likewise, 2a, 2b, 2c and 2d, 3a, 3b, 3c and 3d, 4a, 4b, 4c and 4d are also divided into a set of harmonic diffractive lens sub-units, respectively. It is clear that although 1a, 1b, 1c and 1d are located at different positions, they may converge to the same focal point, as each of the other sets of harmonic diffractive lens sub-elements also has its own focal point. Of course, fig. 5 and 6 are merely exemplary, and in practice, the number of harmonic diffractive lens sub-elements will be very large, as will the number of groups of harmonic diffractive lens sub-elements.
Fig. 7 is a schematic structural view of a harmonic diffraction element used in the viewing angle modulator of the present invention. As described in the background, the nano-grating is used to realize 3D display, and has low diffraction efficiency and low light utilization rate. Therefore, a harmonic diffraction element is adopted as the viewing angle modulator in the present invention. The harmonic diffractive lens subunit is part of the harmonic diffractive element.
Harmonic diffraction utilizes diffracted light of higher orders, so harmonic diffraction elements have a higher surface structure height than ordinary DOEs, typically P (P is a positive integer greater than 1) times the height of an ordinary DOE. As shown in FIG. 7, the left side is the harmonic diffractive element and the right side is the ordinary diffractive element. When designing the harmonic diffraction element, the plurality of target wavelength bands are made to have the same optical power by changing the harmonic diffraction coefficients, and the structure thereof is as shown in fig. 7.
For a conventional diffractive optical element, when light having a certain bandwidth is incident on the structure, the wavelength versus focal length is:
λ0i.e. the design wavelength of the diffractive element, f0Is the focal length of the diffractive element. The optical path difference between adjacent annular zones of the harmonic diffraction element structure is an integral multiple of the wavelength, and the used higher-order diffracted light forms an image, so that the corresponding focuses of the light with other wavelengths are as follows:
in the above formula, P (P > 1) is the harmonic diffraction coefficient, when f0When the coefficient of the front surface is 1, the corresponding wavelengths λ and λ0The focal points of (a) coincide. When the wavelength λ satisfies
When λ is harmonic diffraction wavelength, the diffraction efficiency of the wavelength reaches maximum value, and the focus and λ0The focal points of (a) coincide.
The height of the structure of the harmonic diffraction element is P times that of the ordinary DOE, i.e.
The phase delay is also P times, i.e.:
by substituting the phase delay of the harmonic diffraction element into the previous diffraction efficiency expression, the diffraction efficiency expression of the harmonic diffraction element can be obtained as follows:
it is obvious from the formula that the maximum diffraction efficiency of the first diffraction order cannot be reached when the maximum diffraction efficiency has been reached due to the change of the phase height and the condition that the maximum diffraction efficiency has been reached has been changed
The corresponding wavelengths have maximum efficiency values, and the focus point coincides with the main focus, and the wavelengths are harmonic diffraction wavelengths.
FIG. 8 is a diffraction efficiency plot for a harmonic diffraction element with a center wavelength of 632 nm. As shown in fig. 8, a harmonic diffraction element with a central wavelength of 632nm is selected, and the diffraction efficiency reaches a maximum at the central wavelength, and decreases towards both sides of the central wavelength, as the coefficients of the harmonic diffraction element increase sequentially, the areas covered by both sides of the central wavelength decrease with the increase of the coefficients.
FIG. 9 is a graph of the diffraction efficiency of a harmonic diffraction element with a center wavelength of 700 nm; selecting the center wavelength of 700nm, the harmonic diffraction coefficient of 5 and the corresponding harmonic diffraction wavelength
Thus, the maximum efficiency value is shown in the graph of fig. 9 at 583nm for m =6, 500nm for m =7, and 437nm for m = 8.
It can be seen from the above figure that a particular wavelength within a band around a harmonic diffraction wavelength has a greater diffraction efficiency and that different wavelengths correspond to different orders, the greater the diffraction order, the smaller the band covered. In some applications, for example, when the harmonic diffraction element is applied to liquid crystal display, the filter of the liquid crystal corresponds to three RGB colors, and the corresponding harmonic diffraction structure is designed for the three RGB colors, so that three-color emergent light of the liquid crystal can be converged at the same point in space, and a certain achromatic effect can be achieved.
FIG. 10 is a graph of the fractional-band diffraction efficiency of a harmonic diffraction element centered at 700 nm. Selecting a harmonic diffraction element with the central wavelength of 700nm, the harmonic diffraction coefficient of 5 and the focal length of the central wavelength of 100mm, and only selecting a waveband with the efficiency of more than 40% for simulation, wherein the curve 10: the central wavelength and the wide-range wave bands at two sides of the central wavelength corresponding to different orders in the figure have larger diffraction efficiency (more than 40 percent), the theoretical offset of the focal length is less than 10 percent, and the central wavelength and the wide-range wave bands at two sides of the central wavelength can be approximately regarded as that the continuous wave bands have common focuses.
In one embodiment, the naked eye three-dimensional display apparatus further includes an aperture array diaphragm between the display part 410 and the viewing angle adjusting device 420. The aperture array diaphragm includes apertures 951 arranged in an array, each aperture may correspond to a display pixel (e.g., a light emitting diode), and light emitted by a display pixel is transmitted to a corresponding viewing angle adjusting unit through the corresponding aperture. The shape of the aperture may be square, circular, polygonal, but circular is preferred in view of the symmetry of the light. Preferably, at this time, a diameter of a side of the aperture facing the display part is smaller than a diameter of a side of the aperture facing the viewing angle regulating unit.
The method of manufacturing the diffraction element is described below.
The surface phase distribution of the common spherical lens can be the superposition of a plurality of 2 pi, and different phases can cause light rays to be bent to different degrees. Not generally, a parabola is taken as an example, and a parabolic curved surface is shown in fig. 11.
And performing collapse calculation on the calculated quadric surface, dividing the phase of the lens surface by taking 2 pi as a unit, performing collapse again, removing the phase of integral multiple of 2 pi to leave a remainder, wherein the remainder is 0-2 pi distribution, and finally forming a concentric ring, such as a Fresnel structure formed in figure 12, wherein the phase delay of each ring zone period is 2 pi, and because the slopes of the inclined planes of the quadric surface under different radii are different, the period of the diffraction structure after collapse is reduced along with the increase of the radii, and when the period is small to a certain degree, the processing limit is reached. FIG. 12 is a schematic of quadric collapse.
The surface of the prism is composed of a series of sawtooth prisms when viewed in cross section, and the central part is an elliptic arc. Each prism has a different angle with the adjacent prism, but concentrates the light to form a central focus, i.e. the focus of the lens, and the height of the prism is related to the central wavelength and is specifically the height
And n is the refractive index.
When the unit height of collapse is an integer multiple of the wavelength, i.e. if the unit of collapse of the prism is P x 2 pi, the radii of all concentric rings are correspondingly enlarged simultaneously, and the prism height is also enlarged P times simultaneously.
The diffraction structure formed at this time is a harmonic diffraction element, but the focal length is still unchanged, and the focal lengths of the rest wavelengths have the relation with the focal length of the central wavelength
And m is other diffraction orders, so that the coefficient of the focal length is 1, the focus of the mth order of other wavelengths is superposed with the central wavelength, and the light with a plurality of wavelengths is converged at the same point, thereby achieving the purpose of eliminating chromatic dispersion.
Compared with a diffraction element, the slope of the opposite annular slope is the same, but the phase delay of the harmonic diffraction element is higher, so that the period of the harmonic diffraction element is larger than that of the diffraction element at the same radius, and the processing difficulty is reduced to a certain extent. The formula of the radius of the diffraction element and the harmonic diffraction element can also be derived according to the formula of the curved surface of the spherical lens, as shown in fig. 13. FIG. 13 is a schematic diagram of a radius formula of a diffraction element and a harmonic diffraction element.
Fig. 14 is a schematic of collapse calculation. Assuming that the radius of the spherical surface is R, the focal length of the plano-convex spherical lens is
Collapsing the curved surface of the lens, each collapseIs a center wavelength, the jth zone is collapsed j times, and the radius of the jth zone is assumed to be ajAccording to the triangular relationship:
unfolding to obtain:
wherein
Small relative to 2R, and can be neglected to approximate, then the radius after approximation is expressed as:
obtaining an intuitive radius formula similar to a Fresnel zone plate, if a harmonic diffraction structure needs to be calculated, only multiplying the collapsed height by a harmonic diffraction coefficient P, wherein the radius formula at the moment is
As can be seen from the radius formula, the period of the structure is obviously enlarged by the expansion factor of
And (4) doubling. The period of the structure can be deduced by the radius formula of the diffraction structure as follows:
for example, the structural period of a diffraction element with a central wavelength of 532nm, a focal length of 100mm and an aperture of 10mm is calculated: substituting the wavelength, the focal length and the radius into a formula, calculating to obtain the serial number of a ring belt at the position of 10mm of the caliber, wherein the serial number is 235, and substituting the serial number of the ring belt into a period formula to calculate the period to be 10.65 mu m; in the case of a structure having a harmonic diffraction coefficient of 5, the period is 23.8. mu.m.
When the diffractive element is used for naked eye 3D display, the periodic modulation accuracy of adjacent pixels can be calculated. If the display pixels are assumed to be 100 μm and the number of viewpoints is 4, the radius difference between adjacent pixels is 200 μm, the adjacent pixels are located at a radius of 100mm, and the observation distance, i.e. the focal length, is 300mm, the period difference between the two pixels is 0.33 μm according to a calculation formula; in the case of a structure having a harmonic diffraction coefficient of 5, the period difference is 0.74. mu.m. Therefore, the precision of the processing equipment needs to be more than 0.74 μm to meet the requirement of the periodic precision modulation of adjacent pixels. FIG. 15 is a schematic diagram of a harmonic diffractive lens structure.
As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, including not only those elements listed, but also other elements not expressly listed.
In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.
The features of the embodiments and embodiments described herein above may be combined with each other without conflict.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. A naked eye three dimensional display device, comprising:
a display section including a display cell array in which a plurality of display cell arrays are arranged;
a viewing angle regulating device including a harmonic diffraction lens array formed by arranging a plurality of harmonic diffraction lens sub-unit arrays,
each harmonic diffraction lens subunit corresponds to one display unit, the harmonic diffraction lens subunits of the harmonic diffraction lens array are divided into a plurality of groups, light rays emitted by the same group of harmonic diffraction lens subunits can converge into the same viewpoint, and light rays emitted by different groups of harmonic diffraction lens subunits can converge into different viewpoints.
2. The naked-eye three-dimensional display device of claim 1, wherein the display elements corresponding to each group of harmonic diffractive lens sub-units display images at one viewing angle, and the display elements corresponding to different groups of harmonic diffractive lens sub-units display images at different viewing angles.
3. The naked eye three-dimensional display device of claim 1, wherein the harmonic diffractive lens sub-elements belonging to the same group are scattered and distributed at different positions, the harmonic diffractive lens sub-elements belonging to different groups are arranged in a staggered manner,
one of the harmonic diffractive lens sub-units of each of the sets of harmonic diffractive lens sub-units is disposed adjacent to one of the harmonic diffractive lens sub-units of the other set of harmonic diffractive lens sub-units to form a harmonic diffractive lens sub-unit combination.
4. The naked eye three dimensional display apparatus of claim 1,
the height d of the surface structure of the harmonic diffraction lens subunitHComprises the following steps:
p is a harmonic diffraction coefficient and is an integer value of 2 or more,
in order to design a target wavelength of light,
for designing refractive index of light wave with target wavelength in medium。
5. The naked eye three dimensional display apparatus of claim 1,
when a user watches the display part at a first position, one eye of the user is positioned at a first viewpoint and can see the light rays emitted by the first group of harmonic diffraction lens subunits, and the other eye is positioned at a second viewpoint and can see the light rays emitted by the second group of harmonic diffraction lens subunits, so that the user can see two images with different viewing angles at the first position to form a first three-dimensional image in the brain of the user;
when a user watches the display part at the second position, one eye of the user is positioned at the third viewpoint and can see the light rays emitted by the third group of harmonic diffraction lens subunits, and the other eye is positioned at the fourth viewpoint and can see the light rays emitted by the fourth group of harmonic diffraction lens subunits, so that the user can see other two images with different visual angles at the second position to form a second three-dimensional image, wherein the visual angles of the first three-dimensional image and the second three-dimensional image are different.
6. The naked eye three dimensional display apparatus of claim 1,
the display element is one or more display pixels,
the display pixels are LED pixels or LCD pixels.
7. The naked eye three-dimensional display device of claim 1, wherein the display unit comprises at least a red pixel, a blue pixel and a green pixel, and light rays emitted by the red pixel, the blue pixel and the green pixel of the same display unit are converged after passing through the same harmonic diffraction lens sub-unit.
8. The naked eye three dimensional display device of claim 1, further comprising:
and the aperture array diaphragm is positioned between the display part and the visual angle regulating device and comprises apertures which are arranged into an array, each aperture corresponds to one display unit, and light rays emitted by one display unit are transmitted to the corresponding harmonic diffraction lens subunit through the corresponding aperture.
9. The naked eye three dimensional display apparatus of claim 8,
the diameter of the side of the aperture facing the display unit is smaller than the diameter of the side of the aperture facing the harmonic diffractive lens sub-unit,
the aperture is in the shape of a circular column, a square column or a polygonal column.
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