CN111045213B - Light field display device and display method thereof - Google Patents

Abstract

The invention discloses a light field display device and a display method thereof, wherein a system control element is used for controlling an image rendering element to render a display image according to a set time sequence according to three-dimensional position information obtained by a sight tracking element so as to enable the display image to accord with the visual effect of a human eye focusing plane, and controlling a focal length adjusting element to adjust the focal length according to the set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes; a display element for emitting light rays carrying image information of the rendered display image; the focal length adjusting element is used for emitting the light emitted by the display element to the projection lens; the projection lens is used for projecting the light rays emitted by the focal length adjusting element to the optical element; and the optical element is used for emitting the light rays projected by the projection lens to human eyes. Through the focusing adjustment of a plurality of imaging surfaces within a certain depth range, a natural 3D image is presented, and eye fatigue and dizziness caused by long-term watching of human eyes are avoided.

Description

Light field display device and display method thereof

Technical Field

The invention relates to the technical field of display, in particular to a light field display device and a display method thereof.

Background

In the current near-eye display field, when a user wears a near-eye display device, a displayed three-dimensional (3D) object is a stereoscopic vision formed by displaying different images to the left and right eyes of the user, since the 3D display based on binocular stereo vision has a problem of convergence adjustment conflict, as shown in fig. 1, when the human eyes watch objects in the real world, the focusing distances of the human eyes are identical to the convergence distance, as shown in fig. 2, when the human eye views the display screen, the focusing distance of the human eye is the distance between the human eye and the display screen, while the convergence distance of the human eyes is the distance between the human eyes and the virtual image displayed in 3D, as is apparent from fig. 2, the difference between the convergence distance and the convergence distance of the human eyes is large, the user can cause fatigue and dizziness of eyes when wearing the near-eye display device for a long time, which is a problem to be solved urgently in stereoscopic display.

Disclosure of Invention

The embodiment of the invention provides a light field display device and a display method thereof, which are used for solving the problems of fatigue and dizziness of eyes caused when a user wears near-eye display equipment for a long time in the prior art.

In a first aspect, an embodiment of the present invention provides a light field display device, including: the system comprises a sight tracking element, an image rendering element, a display element, a focal length adjusting element positioned on one side of a light emitting surface of the display element, a projection lens positioned on an optical path of the focal length adjusting element, an optical element positioned on the optical path of the projection lens and a system control element;

the sight tracking element is used for detecting three-dimensional position information of a fixation point of the human eye;

the system control element is used for controlling the image rendering element to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element so that the display image conforms to the visual effect of a human eye focusing plane, and controlling the focal length adjusting element to adjust the focal length according to the set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

the display element is used for emitting light rays carrying image information of rendered display images;

the focal length adjusting element is used for emitting the light emitted by the display element to the projection lens;

the projection lens is used for projecting the light rays emitted by the focal length adjusting element to the optical element;

the optical element is used for emitting the light rays projected by the projection lens to human eyes.

In a possible implementation manner, in the light field display device provided in an embodiment of the present invention, the optical element includes: a polarization beam splitter, a phase retarder, and a reflecting element;

the polarization beam splitting element is used for emitting the light rays projected by the projection lens to the phase retarder and emitting the light rays emitted by the phase retarder to human eyes;

the phase retarder is used for emitting the light emitted by the polarization light splitting element to the reflecting element and emitting the light reflected by the reflecting element to the polarization light splitting element.

In a possible implementation manner, in the light field display device provided in the embodiment of the present invention, the light emitted by the display element is natural light;

the phase retarder includes: a first phase retarder positioned on one side of the polarization splitting element in the first direction, and a second phase retarder positioned on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in the first direction, and a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a direction different from the first direction;

the first reflecting element and the second reflecting element have the same focal power, and the first reflecting element and the second reflecting element are symmetrically arranged relative to the polarization light splitting element;

the polarization light splitting element is used for splitting light emitted by the projection lens into first linearly polarized light and second linearly polarized light, reflecting the first linearly polarized light to the first phase retarder, transmitting the second linearly polarized light to the second phase retarder, transmitting the second linearly polarized light emitted by the first phase retarder to human eyes, and reflecting the first linearly polarized light emitted by the second phase retarder to the human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into the first linearly polarized light.

In a possible implementation manner, in the light field display device provided in the embodiment of the present invention, the light field display device further includes: a polarization conversion element located between the display element and the focus adjustment element;

the light emitted by the display element is natural light;

the system control element is further used for controlling the polarization conversion element to convert the light emitted by the display element into first linearly polarized light in n time sequences from 1 to n, and to convert the light emitted by the display element into second linearly polarized light in n time sequences from n +1 to 2 n; wherein n is the number of variable focuses of the focus adjustment element;

the phase retarder includes: a first phase retarder positioned on one side of the polarization splitting element in the first direction, and a second phase retarder positioned on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in the first direction, and a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a different direction from the first direction;

the first reflective element and the second reflective element have different optical powers;

the polarization beam splitting element is used for splitting the light emitted by the projection lens into first linearly polarized light and second linearly polarized light, reflecting the first linearly polarized light to the first phase retarder, transmitting the second linearly polarized light to the second phase retarder, transmitting the second linearly polarized light emitted by the first phase retarder to human eyes, and reflecting the first linearly polarized light emitted by the second phase retarder to the human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into the first linearly polarized light.

In a possible implementation manner, in the light field display device provided in the embodiment of the present invention, the light emitted by the display element is a first linearly polarized light;

the phase retarder includes: a first phase retarder located on one side of the polarization splitting element in a first direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in a first direction;

the polarization beam splitting element is used for reflecting the first linearly polarized light to the first phase retarder and transmitting the second linearly polarized light emitted by the first phase retarder to human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light.

In a possible implementation manner, in the light field display device provided in the embodiment of the present invention, the light emitted by the display element is a second linearly polarized light;

the phase retarder includes: a second phase retarder located on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a different direction from the first direction;

the polarization beam splitting element is used for transmitting the second linearly polarized light to the second phase retarder and reflecting the first linearly polarized light emitted by the second phase retarder to human eyes;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into the first linearly polarized light.

In a possible implementation manner, in the light field display device provided by the embodiment of the present invention, the first reflective element is a transflective element.

In a possible implementation manner, in the light field display device provided in an embodiment of the present invention, the focal length adjustment element includes: a first liquid crystal layer and a second liquid crystal layer which are arranged in a stacked manner;

the initial orientations of the liquid crystals in the first liquid crystal layer and the second liquid crystal layer are orthogonal to each other.

In a possible implementation manner, in the light field display device provided in an embodiment of the present invention, the gaze tracking element includes: an infrared transmitter and an infrared receiver.

In a second aspect, an embodiment of the present invention further provides a display method of the light field display apparatus, including:

the sight tracking element detects three-dimensional position information of a human eye fixation point;

the system control element controls the image rendering element to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element, so that the display image accords with the visual effect of a human eye focusing plane;

the system control element controls the focal length adjusting element to adjust the focal length according to a set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

the display element emits light rays carrying image information of the rendered display image.

The invention has the following beneficial effects:

the embodiment of the invention provides a light field display device and a display method thereof, wherein the light field display device comprises: the system comprises a sight tracking element, an image rendering element, a display element, a focal length adjusting element positioned on one side of a light-emitting surface of the display element, a projection lens positioned on an optical path of the focal length adjusting element, an optical element positioned on the optical path of the projection lens and a system control element; the sight tracking element is used for detecting three-dimensional position information of a fixation point of the human eye; the system control element is used for controlling the image rendering element to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element so that the display image accords with the visual effect of a human eye focusing plane, and controlling the focal length adjusting element to adjust the focal length according to the set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes; a display element for emitting light rays carrying image information of the rendered display image; the focal length adjusting element is used for emitting the light emitted by the display element to the projection lens; the projection lens is used for projecting the light rays emitted by the focal length adjusting element to the optical element; and the optical element is used for emitting the light rays projected by the projection lens to human eyes. According to the light field display device provided by the embodiment of the invention, the three-dimensional information of the human eye fixation point is detected through the sight tracking element, the system control element can control the image rendering element to render the image according to the set time sequence according to the three-dimensional position information of the human eye fixation point, so that the displayed image accords with the visual effect of the human eye focusing plane, and the focal length is adjusted according to the set time sequence through controlling the focal length adjusting element, so that the focal length adjustment of the whole optical system is realized, the focusing adjustment of a plurality of imaging surfaces in a certain depth range can be realized, a natural 3D image is presented, the displayed image accords with the visual mechanism of human eyes, and the eye fatigue and dizziness caused by long-term watching of human eyes can be avoided.

Drawings

Fig. 1 is a schematic view showing the relationship between the focusing distance and the convergence distance when the human eyes watch the objects in the real world;

FIG. 2 is a schematic view showing the relationship between the focusing distance and the convergence distance when the human eyes watch the display screen in the prior art;

fig. 3 is a schematic structural diagram of a light field display device according to a first implementation manner in the embodiment of the present invention;

fig. 4 is a schematic structural diagram of a light field display device according to a second implementation manner in the embodiment of the present invention;

fig. 5 is a workflow of a second implementation manner in the embodiment of the present invention;

fig. 6 is a schematic structural diagram of a light field display device according to a third implementation manner in the embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of a light field display device according to a fourth implementation manner in the embodiment of the present invention;

FIGS. 8 and 9 are schematic diagrams illustrating phase modulation of a liquid crystal layer, respectively;

FIG. 10 is a schematic diagram of driving a liquid crystal layer to achieve multiple phase profile modulation;

fig. 11 is a flowchart of a display method of the light field display device according to an embodiment of the present invention.

Detailed Description

The embodiment of the invention provides a light field display device and a display method thereof, aiming at the problems of eye fatigue and dizziness caused when a user wears near-eye display equipment for a long time in the prior art.

The following describes in detail a specific embodiment of a light field display device and a display method thereof according to an embodiment of the present invention with reference to the drawings. The thicknesses and shapes of the various film layers in the drawings are not to be considered true proportions, but are merely intended to illustrate the present invention.

In a first aspect, an embodiment of the present invention provides a light field display device, as shown in fig. 3, including: a line-of-sight tracking element 11, an image rendering element 12, a display element 13, a focal length adjusting element 14 located on a light exit surface side of the display element 13, a projection lens 15 located on an optical path of the focal length adjusting element 14, an optical element 16 located on an optical path of the projection lens 15, and a system control element 17;

the sight tracking element 11 is used for detecting three-dimensional position information of a fixation point of a human eye;

the system control element 17 is used for controlling the image rendering element 12 to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element 11 so as to enable the display image to accord with the visual effect of a human eye focusing plane, and controlling the focal length adjusting element 14 to adjust the focal length according to the set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

a display element 13 for emitting light rays carrying image information of the rendered display image;

a focal length adjusting element 14 for directing the light emitted from the display element to a projection lens 15;

a projection lens 15 for projecting the light emitted from the focal length adjusting element 14 to the optical element 16;

and an optical element 16 for emitting the light projected by the projection lens 15 to the human eye 10.

The light field display device provided by the embodiment of the invention detects the three-dimensional information of the human eye fixation point through the sight tracking element, the system control element can control the image rendering element to render the image according to the set time sequence according to the three-dimensional position information of the human eye fixation point, so that the displayed image accords with the visual effect of the human eye focusing plane, and the focal length is adjusted according to the set time sequence by controlling the focal length adjusting element, so that the focal length adjustment of the whole optical system is realized, the focusing adjustment of a plurality of imaging surfaces in a certain depth range can be realized, a natural 3D image is presented, the displayed image accords with the visual mechanism of the human eye, and the eye fatigue and dizziness caused by long-term watching of the human eye can be avoided.

The light field display apparatus provided in the embodiment of the present invention may be applied to a near-eye display device, for example, may be applied to an Augmented Reality (AR) display device, may also be applied to a Virtual Reality (VR) display device, or may also be applied to other display devices, which is not limited herein.

The focal length adjusting element 14 can realize modulation of a plurality of phase topographies under the control of the system control element 17, so that the focal length adjusting element 14 can be controlled to adjust the focal length according to a set time sequence according to the three-dimensional position information of the fixation point of the human eye, so as to change the focal length of the whole optical system, and a plurality of imaging surfaces, namely, imaging surfaces Q1 and Q2 … … Qn in fig. 3 can be formed spatially.

Specifically, in the light field display device according to an embodiment of the present invention, the sight-line tracking element 11 includes: an infrared transmitter 111 and an infrared receiver 112. The infrared light emitted by the infrared emitter 111 is reflected by the human eye 10 and then collected by the infrared receiver 112, the gaze fixation point can be obtained through the vector between the pupil center and the corneal reflection, and the gaze information of the human eye can be obtained through data analysis processing, so that the three-dimensional position information of the gaze fixation point of the human eye can be obtained. Specifically, the infrared receiver 112 may be an infrared camera, and may also be other infrared receiving devices, which is not limited herein.

By adopting a time division multiplexing mode, the system control element 17 can control the image rendering element 12 to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element 11, so that the display image conforms to the visual effect of the human eye focusing plane. The image rendering component 12 transmits the rendered display image to the display component 13 according to a set time sequence, the display component 13 may have a high refresh rate, and the display component 13 may emit light carrying image information of the rendered display image.

The system control element 17 can also control the focal length adjusting element 14 to adjust the focal length according to the set time sequence according to the three-dimensional position information obtained by the sight tracking element 11, thereby changing the focal length of the whole optical system, and realizing the adjustment of the imaging plane according to the focal length plane of the human eye, the light ray carrying the image information and emitted by the display element 13 passes through the focal length adjusting element 14, the projection lens 15 and the optical element 16 and is imaged on each imaging plane Q1-Qn, and the total time length of the set time sequence corresponding to each display period is less than the refreshing time of the human eye, generally, the refreshing time of the human eye is about 1/30 seconds, so that the images formed by the imaging planes Q1-Qn can be subjected to depth fusion to form the image on the fixation point plane, and the position of the perception plane of the depth fusion can be changed along with the position change of the fixation point of the human eye, thereby forming natural light field 3D display, the visual fatigue of human eyes can be relieved.

In a specific implementation, each display period may include a plurality of time sequences, for example, when each display period includes n time sequences, in order to form a better 3D display effect, the total duration of the n time sequences in each display period needs to be less than the refresh time of human eyes.

Further, with reference to fig. 3, the light field display device provided by the embodiment of the present invention includes an optical element 16, including: a polarization splitting element 161, phase retarders (162 a and 162b in the figure) and reflecting elements (163 a and 163b in the figure);

a polarization beam splitter 161 for directing the light projected by the projection lens 15 to the phase retarder and directing the light emitted from the phase retarder to the human eye 10;

and a phase retarder for directing the light emitted from the polarization splitting element 161 to the reflecting element and directing the light reflected by the reflecting element to the polarization splitting element.

The polarization splitting element 161 may reflect the first linearly polarized light and transmit the second linearly polarized light, so that the natural light emitted to the polarization splitting element 161 may be split into two light beams, specifically, the first linearly polarized light is s light, and the second linearly polarized light is p light, or the first linearly polarized light is p light and the second linearly polarized light is s light, which is not limited herein, and the first linearly polarized light is s light and the second linearly polarized light is p light in the embodiment of the present invention. In addition, since the polarization beam splitter 161 has no optical energy loss, the light field display device in the embodiment of the present invention has high optical efficiency.

The light projected by the projection lens 15 is emitted to the polarization beam splitter 161, reflected or transmitted by the polarization beam splitter 161 and emitted to the phase retarder, the light is emitted to the reflection element after passing through the phase retarder, the light is reflected by the reflection element and emitted to the phase retarder again, then emitted to the human eye 10 after passing through the phase retarder and the polarization beam splitter 161, and the light path is folded by the polarization beam splitter 161, so that the overall size of the light field display device can be reduced, and the light field display device is miniaturized and thinned.

The following detailed description of specific implementations of the light field display device according to the embodiments of the present invention is provided with reference to the accompanying drawings:

the implementation mode is as follows:

as shown in fig. 3, the light emitted from the display element 13 is natural light;

a phase retarder comprising: a first phase retarder 162a located on one side of the polarization splitting element 161 in the first direction x, and a second phase retarder 162b located on one side of the polarization splitting element 161 in the second direction y;

a reflective element, comprising: a first reflecting element 163a located on one side of the polarization splitting element 161 in the first direction x, and a second reflecting element 163b located on one side of the polarization splitting element 161 in the second direction y; the second direction y is a different direction from the first direction x; in the drawings, the first direction x is perpendicular to the second direction y, which is taken as an example for illustration, and in the specific implementation, the first direction x and the second direction y may also be not perpendicular to each other, and are not limited herein.

The first and second reflection elements 163a and 163b have the same optical power, and the first and second reflection elements 163a and 163b are symmetrically disposed with respect to the polarization splitting element 161;

the polarization beam splitter 161 is configured to split the light emitted from the projection lens 15 into a first linearly polarized light s and a second linearly polarized light p, reflect the first linearly polarized light s to the first phase retarder 162a, transmit the second linearly polarized light p to the second phase retarder 162b, transmit the second linearly polarized light p emitted from the first phase retarder 162a to the human eye 10, and reflect the first linearly polarized light s emitted from the second phase retarder 162b to the human eye;

a first phase retarder 162a for converting the first linearly polarized light s emitted from the polarization beam splitter 161 into circularly polarized light, and converting the circularly polarized light reflected by the first reflecting element 163a into a second linearly polarized light p;

and a second phase retarder 162b for converting the second linearly polarized light p emitted from the polarization beam splitter 161 into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element 163b into the first linearly polarized light s.

The system control element 17 controls the image rendering element 12 to render the corresponding display image according to the set time sequence according to the three-dimensional position information of the human eye gaze point provided by the gaze tracking element 11, so that the display image conforms to the visual effect of the human eye focal plane, and the system control element 17 also controls the focal length adjusting element 14 to adjust the focal length according to the set time sequence according to the three-dimensional position information of the human eye gaze point.

The light emitted by the display element 13 is natural light, that is, the light emitted by the display element includes both the first linear polarized light s and the second linear polarized light p, the natural light carrying image information and emitted by the display element 13 is transmitted to the polarization beam splitter 161 through the focal length adjustment element 14 and the projection lens 15, the polarization beam splitter 161 splits the light into the first linear polarized light s and the second linear polarized light p, reflects the first linear polarized light s to the first phase retarder 162a, and transmits the second linear polarized light p to the second phase retarder 162b, that is, the light is split by the polarization beam splitter 161 and then enters two optical paths, specifically, the reflected first linear polarized light s is changed into circular polarized light after passing through the first phase retarder 162a, in this embodiment of the present invention, the first phase retarder 162a and the second phase retarder 162b may be quarter-wave plates, therefore, the linearly polarized light can be converted into circularly polarized light, the circularly polarized light emitted from the first phase retarder 162a is reflected by the reflection surface Ta of the first reflection element 163a, and then passes through the first phase retarder 162a again to be converted into the second linearly polarized light p, and the second linearly polarized light p is transmitted by the polarization beam splitter 161 and then enters the human eye 10. The transmitted second linearly polarized light p passes through the second phase retardation plate 162b and then becomes circularly polarized light, the circularly polarized light emitted from the second phase retardation plate 162b is reflected by the reflection surface Tb of the second reflection element 163b, and then passes through the second phase retardation plate 162b again and becomes the first linearly polarized light s, and the first linearly polarized light s passes through the polarization beam splitter 161 and then enters the human eye 10.

In the first implementation manner of the embodiment of the present invention, since the first reflective element 163a and the second reflective element 163b have the same optical power, and the first reflective element 163 and the second reflective element 163b are symmetrically disposed with respect to the polarization splitting element 161, the reflection optical path and the transmission optical path passing through the polarization splitting element 161 are symmetric about the polarization splitting element 161, that is, the optical paths of the two optical paths are equal, so that the display images formed by the light rays in the two polarization states respectively entering the human eye through the two optical paths are overlapped on the same image plane. In addition, as shown in fig. 3, the reflecting surfaces of the first reflecting element 163a and the second reflecting element 163b are curved surfaces, so that the light rays are converged, and the reflected light rays of the first reflecting element 163a or the second reflecting element 163b can be converged to the position of the human eye 10.

Since the system control unit 17 controls the focal length adjusting unit to adjust the focal length according to the set timing based on the three-dimensional position information of the fixation point of the human eye, thereby realizing the focal length adjustment of the focal length adjusting element 14 to the whole light field display device, and adjusting the imaging plane to the human eye focusing plane in real time according to the human eye focusing plane acquired by the sight tracking element 11, and controls the image rendering element 12 to render the required display image through the system control element 17, so as to obtain the image display which is in accordance with the adjustment of the monocular focal length of the human eyes, can realize the monocular focusing function of human eyes, and the displayed virtual object can generate focusing and blurring effects along with the difference of the fixation points of the human eyes along with the change of the fixation points of the human eyes, the display is in accordance with the visual characteristics of human eyes, and the light field display is realized, so that the visual fatigue of the human eyes is relieved.

In addition, the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes, so that the human eyes can be ensured not to feel the focal length change of the light field display device, n imaging planes of Q1-Qn can be formed in each display period, n is the variable focal length number of the focal length adjusting element 14, and the total duration of the n time sequences in each display period is less than the refreshing time of the human eyes.

The light emitted by the display element 13 passes through the focal length adjusting element 14, the projection lens 15 and the polarization beam splitting element 161, and then is reflected and transmitted to enter the two light paths respectively, and the light returned from the two light paths is finally received by the human eyes 10, so that the loss of light energy is reduced, the overall light effect of the light field display device is higher, a high-light-effect near-to-eye display system can be realized, the requirement on the brightness of the display element 13 is reduced, the energy consumption is reduced, and the portability of the near-to-eye display system is improved.

Further, the polarization beam splitter 161 has no optical energy loss with respect to light, and can further improve the optical efficiency of the light field display device, for example, without considering surface reflection and other absorption loss of each light element except the light splitter and the reflection element in light propagation, if a common light splitter is used, the optical efficiency of the entire display device is 12.5% (light passes through the twice light splitter and the once reflection surface), if a polarization beam splitter is used, since there is no optical energy loss through the polarization beam splitter, there is optical energy loss only at the reflection surface of the reflection element, the optical efficiency of the optical path through the first reflection element is 25%, and the optical efficiency of the optical path through the second reflection element is 50%, the theoretical optical efficiency of the display device is 75%, therefore, the embodiment of the present invention employs the polarization beam splitter, the theoretical light effect is improved by 6 times.

Implementation mode two

As shown in fig. 4, the light field display apparatus provided in the embodiment of the present invention may further include: a polarization conversion element 18 located between the display element 13 and the focus adjustment element 14;

the light emitted from the display element 13 is natural light;

the system control element 17 is further configured to control the polarization conversion element 18 to convert the light emitted by the display element 13 into first linearly polarized light s in n time sequences of 1 to n, and to convert the light emitted by the display element 13 into second linearly polarized light p in n time sequences of n +1 to 2 n; wherein n is the variable focus number of the focal length adjusting element;

a phase retarder comprising: a first phase retarder 162a located on one side of the polarization splitting element 161 in the first direction x, and a second phase retarder 162b located on one side of the polarization splitting element 161 in the second direction y;

a reflective element, comprising: a first reflecting element 163a located on one side of the polarization splitting element 161 in the first direction x, and a second reflecting element 163b located on one side of the polarization splitting element 161 in the second direction y; the second direction y is a different direction from the first direction x;

the first and second reflective elements 163a and 163b have different optical powers;

the polarization beam splitter 161 is configured to split light emitted from the projection lens 15 into a first linearly polarized light s and a second linearly polarized light p, reflect the first linearly polarized light s to the first phase retarder 162a, transmit the second linearly polarized light p to the second phase retarder 162b, transmit the second linearly polarized light p emitted from the first phase retarder 162a to human eyes, and reflect the first linearly polarized light s emitted from the second phase retarder 162b to human eyes;

a first phase retarder 162a for converting the first linearly polarized light s emitted from the polarization beam splitter 161 into circularly polarized light, and converting the circularly polarized light reflected by the first reflecting element 163a into a second linearly polarized light p;

and a second phase retarder 162b for converting the second linearly polarized light p emitted from the polarization beam splitter 161 into circularly polarized light and converting the circularly polarized light reflected by the second reflector 163b into the first linearly polarized light s.

In a second implementation manner of the embodiment of the present invention, in order to solve the problem that the number of variable focal lengths of the focal length adjusting element in one display period is limited, for example, in the first implementation manner, when the number of variable focal lengths of the focal length adjusting element in each display period is n, only n image planes can be formed.

In the second implementation manner, a time division multiplexing manner is adopted, according to the three-dimensional position information of the gaze point of the human eye provided by the gaze tracking element 11, the system control element 17 controls the image rendering element 12 to render the corresponding display image according to the set timing sequence, and moreover, the display element 13 with a high refresh rate is adopted, so that the display element 13 can rapidly switch the display image according to the set timing sequence, and the system control element 17 can also control the polarization conversion element 18 to convert the polarization state of the light emitted by the display element 13 into the first linearly polarized light s or the second linearly polarized light p according to the set timing sequence.

Specifically, the polarization conversion element 18 may be controlled to convert the light emitted from the display element 13 into the first linearly polarized light s in n times of sequences 1 to n, and in each time sequence of n from 1 to n, the focal length of the focal length adjusting element 14 is controlled to be changed n times, where n is the number of the variable focal lengths of the focal length adjusting element 14, the first linearly polarized light s is transmitted to the polarization beam splitter 161 through the focal length adjusting element 14 and the projection lens 15, the first linearly polarized light s is reflected by the polarization beam splitter 161 and then transmitted to the first phase retarder 162a to become circularly polarized light, the circularly polarized light is reflected by the reflection surface Ta of the first reflection element 163a and then transmitted to the first phase retarder 162a again, and after passing through the first phase retarder 162a, the circularly polarized light is converted into a second linearly polarized light p, and the obtained second linearly polarized light p is transmitted by the polarization beam splitter 161 and then enters the human eye 10 to form the 1 st to nth imaging surfaces.

The polarization conversion element 18 can be controlled to convert the light emitted by the display element 13 into the second linearly polarized light p in n + 1-2 n time sequences, the focal length of the focal length adjusting element 14 is controlled to change n times in n time sequences from n +1 to 2n, n is the number of the variable focal lengths of the focal length adjusting element 14, the second linearly polarized light p is transmitted by the polarization splitting element 161 and then emitted to the second phase retarder 162b to become circularly polarized light, the circularly polarized light is reflected by the reflecting surface Tb of the second reflecting element 163b and then emitted to the second phase retarder 162b again, after passing through the second phase retarder 162a, the circularly polarized light is converted into the first linearly polarized light s, and the obtained first linearly polarized light s is transmitted by the polarization splitting element 161 and then emitted to the human eye 10 to form the (n + 1) to 2n) th imaging surfaces.

In the second implementation manner, since the first reflective element 163a and the second reflective element 163b have different focal powers, the radii of curvature of the reflective surfaces Ta and Tb are not uniform, so that the imaging surfaces formed by the n +1 th to 2n th timings entering the human eye 10 do not coincide with the imaging surfaces formed by the 1 st to n th timings, and the n +1 th, n +2 th to 2n th imaging surfaces are formed. Therefore, in the second implementation manner in the embodiment of the present invention, in the 2n time sequences in one display period, 2n imaging planes may be formed, where n is the number of variable focuses of the focus adjusting element 14.

Moreover, one display cycle consisting of 2n time sequences is smaller than the refreshing time of human eyes, the refreshing time of human eyes is about 1/30 seconds generally, the human eyes cannot sense the focal length change of the light field display device, the positions of the fixation points of the human eyes are obtained according to the result of the sight tracking element 11, the display images on different imaging surfaces are rendered, the 1 st image to the 2 nd image are subjected to depth fusion to form an image on a fixation point plane, the position of the depth fusion sensing plane can change along with the positions of the fixation points of the human eyes, natural light field 3D display is formed, and the visual fatigue of the human eyes can be relieved.

Fig. 5 is a workflow of a second implementation manner in the embodiment of the present invention, and as shown in fig. 5, the workflow of the second implementation manner includes:

when a display period starts, firstly, at time sequences 1 to n, the system control element controls the image rendering element to render corresponding display images according to the images required to be displayed at time sequence i (i is 1, 2, …, n) according to the three-dimensional position information of the fixation point of human eyes provided by the sight tracking element;

the system control element controls the polarization conversion element to convert the light emitted by the display element into first linearly polarized light s; after the first linearly polarized light s is reflected by the polarization light splitting element, the first linearly polarized light s emits to the first phase delay plate, then is reflected by the reflecting surface of the first reflecting element and passes through the first phase delay plate again, at the moment, the polarization state of the light is changed into second linearly polarized light p, and the second linearly polarized light p enters human eyes after being transmitted by the polarization light splitting element to form 1 st, 2 nd, … th and n th images on 1 st, 2 nd, … th and n imaging surfaces;

at time sequences n +1 to 2n, the system control element controls the image rendering element to render corresponding display images according to the images required to be displayed at time sequence i (i is n +1, n +2, …,2n) according to the three-dimensional position information of the fixation point of human eyes provided by the sight tracking element;

the system control element controls the polarization conversion element to convert the light emitted by the display element into second linearly polarized light p; after the second linearly polarized light p is transmitted by the polarization light splitting element, the second linearly polarized light p emits to the second phase retarder, and then passes through the second phase retarder again by the reflection surface of the second reflection element, at the moment, the polarization state of the light is the first linearly polarized light s, the first linearly polarized light s enters human eyes after being reflected by the polarization light splitting element, and an n +1, n +2, …,2n image is formed on an n +1, n +2, …,2n imaging surface;

and (3) carrying out depth fusion on the 1 st to 2n image plane images to form natural light field 3D display in human eyes.

Implementation mode three

As shown in fig. 6, the light emitted from the display element 13 is a first linearly polarized light s;

a phase retarder comprising: a first phase retarder 162a located on one side of the polarization splitting element 161 in the first direction x;

a reflective element, comprising: a first reflecting element 163a located on one side of the polarization splitting element 161 in the first direction x;

a polarization beam splitter 161 for reflecting the first linearly polarized light s to the first phase retarder 162a and transmitting the second linearly polarized light p emitted from the first phase retarder 162a to the human eye 10;

the first phase retarder 162a is configured to convert the first linearly polarized light s emitted from the polarization beam splitter 161 into circularly polarized light, and convert the circularly polarized light reflected by the first reflecting element 163a into the second linearly polarized light p.

Specifically, a layer of linear polarizer 19 may be attached to the light exit surface of the display element 13, and the transmission axis direction of the linear polarizer 19 may enable the first linearly polarized light s to transmit, so that the light emitted by the display element 13 is the first linearly polarized light s, or if the light emitted by the display element 13 is the first linearly polarized light s, the linear polarizer 19 may be omitted.

Compared with the first implementation mode, the third implementation mode can omit one of the two transmitted optical paths after passing through the polarization beam splitter 161 in the first implementation mode.

Specifically, the principle of realizing the light field display in the third implementation mode is as follows: the system control element 17 controls the image rendering element 12 to render a corresponding display image according to the three-dimensional position information of the fixation point of the human eye provided by the sight line tracking element 11, so that the display image conforms to the visual effect of the focus plane of the human eye, the first linearly polarized light s carrying the image information and emitted by the display element 13 passes through the focal length adjusting element 14 and the projection lens 15, enters the polarization beam splitter element 161, is reflected to the first phase retarder 162a by the polarization beam splitter element 161, becomes circularly polarized light by the first phase retarder 162a, passes through the first phase retarder 162a again after being reflected by the reflection plane Ta of the first reflection element 163a, and is converted into the second linearly polarized light p by the first phase retarder 162a, and the second linearly polarized light p enters the human eye 10 after being transmitted by the polarization beam splitter element 161.

The focal length of the whole light field display device is adjusted by the focal length adjusting element 14, real-time imaging surface adjustment is carried out according to the eye focusing plane obtained by the sight tracking element 11, the imaging surface is adjusted to the eye focusing plane, the image rendering element 12 is controlled by the system control element 17 to render the required display image, and the image display conforming to the eye monocular focal length adjustment is obtained, so that the monocular focusing function of the eyes can be realized, the displayed virtual object can be focused and blurred along with the change of the fixation points of the eyes, the visual characteristics conforming to the eyes are displayed, the light field display is realized, and the visual fatigue of the eyes is relieved.

Implementation mode four

As shown in fig. 7, the light emitted from the display element 13 is a second linearly polarized light p;

a phase retarder, comprising: a second phase retarder 162b located on one side of the polarization splitting element 161 in the second direction y;

a reflective element, comprising: a second reflecting element 163b located on one side of the polarization splitting element 161 in the second direction y; the second direction y is a different direction from the first direction x;

the polarization beam splitting element 161 is used for transmitting the second linearly polarized light p to the second phase retarder 162b and reflecting the first linearly polarized light s emitted by the second phase retarder 162b to human eyes;

and a second phase retarder 162b for converting the second linearly polarized light p emitted from the polarization beam splitter 161 into circularly polarized light and converting the circularly polarized light reflected by the second reflector 163b into the first linearly polarized light s.

Specifically, a layer of linear polarizer 19 may be attached to the light exit surface of the display element 13, and the transmission axis direction of the linear polarizer 19 may allow the second linearly polarized light p to transmit, so that the light emitted from the display element 13 is the second linearly polarized light p, or if the light emitted from the display element 13 is the second linearly polarized light p, the linear polarizer 19 may be omitted.

Compared with the first implementation mode, the fourth implementation mode can omit one of the two reflected light paths after passing through the polarization beam splitter 161 in the first implementation mode.

Specifically, the principle of realizing the light field display in the fourth implementation mode is as follows: the system control element 17 controls the image rendering element 12 to render a corresponding display image according to the three-dimensional position information of the fixation point of the human eye provided by the sight line tracking element 11, so that the display image conforms to the visual effect of the focus plane of the human eye, the second linearly polarized light p carrying the image information and emitted by the display element 13 passes through the focal length adjusting element 14 and the projection lens 15, enters the polarization beam splitting element 161, is transmitted to the second phase retarder 162b through the polarization beam splitting element 161, is changed into circularly polarized light after passing through the second phase retarder 162b, passes through the second phase retarder 162b again after being reflected by the reflection plane Tb of the second reflection element 163b, is changed into the first linearly polarized light s after passing through the second phase retarder 162b, and the first linearly polarized light s enters the human eye 10 after being reflected by the polarization beam splitting element 161.

The focal length of the whole light field display device is adjusted by the focal length adjusting element 14, real-time imaging surface adjustment is carried out according to the eye focusing plane obtained by the sight tracking element 11, the imaging surface is adjusted to the eye focusing plane, the image rendering element 12 is controlled by the system control element 17 to render the required display image, and the image display conforming to the eye monocular focal length adjustment is obtained, so that the monocular focusing function of the eyes can be realized, the displayed virtual object can be focused and blurred along with the change of the fixation points of the eyes, the visual characteristics conforming to the eyes are displayed, the light field display is realized, and the visual fatigue of the eyes is relieved.

In order to prevent each element in the light field display device from being damaged by an external force, a protection element 164 may be provided on one side of the polarization splitting element 161 in the first direction x.

In practical applications, in the light field display devices in the first to third implementation manners provided by the embodiments of the present invention, as shown in fig. 3, fig. 4 and fig. 6, the first reflective element 163a may be a transflective element, that is, the first reflective element 163 may reflect the light of the first phase retarder 162a, and may also transmit the ambient light G, so that the ambient light G may enter the human eye 10 after passing through the first reflective element 163, so that the human eye 10 may observe the superposition of the image of the light field display device and the real environment, and implement augmented reality display based on the light field display.

Further, as shown in fig. 7, with the light field display device in the fourth implementation mode, since the reflection element is not disposed on one side of the polarization splitting element 161 in the first direction x, and since the protection element 164 only has a protection function and has no optical power, the ambient light G is not affected by the protection element 164, and thus the ambient light G can also pass through the protection element 164 to be emitted to the human eye 10, thereby implementing augmented reality display.

In addition, in the fourth implementation mode, only the reflecting surface is adopted for reflecting the display light, and a transflective element is not adopted, so that most of the light can be reflected at the reflecting surface, and the light field display device of the fourth implementation mode has high light efficiency.

In a specific implementation, in the light field display device provided in the embodiment of the invention, the focal length adjusting element may be a liquid crystal zoom element, and different voltages are applied to different positions in a radial direction on a clear aperture of a liquid crystal layer, so as to generate different phase modulations, so as to change a focal length of the focal length adjusting element.

Fig. 8 and 9 are schematic diagrams illustrating phase modulation performed on a liquid crystal layer, and as shown in fig. 8 and 9, different phase modulations are generated by applying different voltages to liquid crystal molecules at different radial positions across the entire clear aperture of the liquid crystal layer.

Since the liquid crystal lens formed by the single liquid crystal layer has birefringence, only phase modulation can be performed on light in a single linear polarization state, but not on light in an orthogonal polarization state, and the liquid crystal lens is required to be applied to natural light, a double liquid crystal layer may be used, and specifically, in the optical field display devices in the first and second implementation manners provided by the embodiment of the present invention, as shown in fig. 3 and 4, the focal length adjusting element 14 includes: a first liquid crystal layer and a second liquid crystal layer which are arranged in a stacked manner; the initial orientations of liquid crystals in the first liquid crystal layer and the second liquid crystal layer are mutually orthogonal, and the first liquid crystal layer and the second liquid crystal layer respectively correspond to orthogonal polarization states under the control of voltage, so that the phase modulation of the non-linear polarization light by the focal length adjusting element is realized, and the focal length adjustment of the light field display device is realized.

Fig. 10 is a schematic diagram of driving a liquid crystal layer to implement modulation of multiple phase profiles, and as shown in fig. 10, the zooming function of the liquid crystal layer can implement modulation of multiple phase profiles by changing the combination of electrodes for applying voltages, so that the liquid crystal lens has the function of a lens with different focal lengths (f, 2f, 4f), and the focal length of the whole light field display device is changed, so that multiple imaging planes can be spatially formed.

In the light field display devices in the third and fourth implementations provided by the embodiment of the present invention, as shown in fig. 6 and 7, since the light beam emitted to the focal length adjusting element 14 is linearly polarized light, the focal length adjusting element in the third and fourth implementations may use a single liquid crystal layer to adjust the focal length, and in addition, the third and fourth implementations may also use a double liquid crystal layer, which is not limited herein.

In a second aspect, based on the same inventive concept, an embodiment of the present invention further provides a display method of the light field display apparatus, where the principle of the display method to solve the problem is similar to that of the light field display apparatus, so that reference may be made to the implementation of the light field display apparatus for implementation of the display method, and repeated details are not repeated.

As shown in fig. 11, the display method of the light field display device according to the embodiment of the present invention includes:

s201, detecting three-dimensional position information of a human eye fixation point by a sight tracking element;

s202, controlling an image rendering element to render a display image according to a set time sequence by a system control element according to three-dimensional position information obtained by a sight tracking element so that the display image conforms to the visual effect of a human eye focusing plane;

s203, the system control element controls the focal length adjusting element to adjust the focal length according to a set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

s204, the display element emits light carrying the rendered image information of the display image.

According to the display method provided by the embodiment of the invention, the focal length adjusting element and the image rendering element zoom element are controlled in a time division multiplexing mode, the superposition display of a plurality of imaging surfaces is realized, the display images of the plurality of imaging surfaces realize the natural light field 3D display through depth fusion, and the near-to-eye display system for the light field display can vividly display a 3D object, provides image information of different depths, so that the focal length of eyes of a user can be adjusted, and the discomfort caused by long-time focusing of human eyes on one plane is avoided.

According to the light field display device and the light field display method, the three-dimensional information of the human eye gaze point is detected through the sight tracking element, the system control element can control the image rendering element to render the image according to the set time sequence according to the three-dimensional position information of the human eye gaze point, so that the displayed image accords with the visual effect of the human eye focusing plane, the focal length is adjusted according to the set time sequence through controlling the focal length adjusting element, the focal length adjustment of the whole optical system is achieved, the focusing adjustment of a plurality of imaging surfaces in a certain depth range can be achieved, a natural 3D image is presented, the displayed image accords with the visual mechanism of human eyes, and eye fatigue and dizziness caused by long-term watching of human eyes can be avoided.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (5)

1. A light field display device, comprising: the system comprises a sight tracking element, an image rendering element, a display element, a focal length adjusting element positioned on one side of a light emitting surface of the display element, a projection lens positioned on an optical path of the focal length adjusting element, an optical element positioned on the optical path of the projection lens and a system control element;

the sight tracking element is used for detecting three-dimensional position information of a fixation point of human eyes;

the system control element is used for controlling the image rendering element to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element so that the display image conforms to the visual effect of a human eye focusing plane, and controlling the focal length adjusting element to adjust the focal length according to the set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

the display element is used for emitting light rays carrying image information of rendered display images;

the focal length adjusting element is used for emitting the light emitted by the display element to the projection lens;

the projection lens is used for projecting the light rays emitted by the focal length adjusting element to the optical element;

the optical element is used for emitting the light rays projected by the projection lens to human eyes;

the optical element includes: a polarization beam splitter, a phase retarder, and a reflecting element;

the polarization beam splitting element is used for emitting the light rays projected by the projection lens to the phase retarder and emitting the light rays emitted by the phase retarder to human eyes;

the phase retarder is used for emitting the light emitted by the polarization light splitting element to the reflecting element and emitting the light reflected by the reflecting element to the polarization light splitting element;

the light field display device at least comprises the following implementation modes:

the implementation mode is as follows:

the light emitted by the display element is natural light;

the phase retarder includes: a first phase retarder positioned on one side of the polarization splitting element in the first direction, and a second phase retarder positioned on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in the first direction, and a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a direction different from the first direction;

the first reflection element and the second reflection element have the same focal power, and the first reflection element and the second reflection element are symmetrically arranged relative to the polarization beam splitting element;

the polarization beam splitting element is used for splitting the light emitted by the projection lens into first linearly polarized light and second linearly polarized light, reflecting the first linearly polarized light to the first phase retarder, transmitting the second linearly polarized light to the second phase retarder, transmitting the second linearly polarized light emitted by the first phase retarder to human eyes, and reflecting the first linearly polarized light emitted by the second phase retarder to the human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into first linearly polarized light; the implementation mode two is as follows:

further comprising: a polarization conversion element located between the display element and the focus adjustment element;

the light emitted by the display element is natural light;

the system control element is further used for controlling the polarization conversion element to convert the light emitted by the display element into first linearly polarized light in n time sequences from 1 to n, and to convert the light emitted by the display element into second linearly polarized light in n time sequences from n +1 to 2 n; wherein n is the number of variable focuses of the focus adjustment element;

the phase retarder includes: a first phase retarder positioned on one side of the polarization splitting element in the first direction, and a second phase retarder positioned on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in the first direction, and a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a different direction from the first direction;

the first reflective element and the second reflective element have different optical powers;

the polarization beam splitting element is used for splitting the light emitted by the projection lens into first linearly polarized light and second linearly polarized light, reflecting the first linearly polarized light to the first phase retarder, transmitting the second linearly polarized light to the second phase retarder, transmitting the second linearly polarized light emitted by the first phase retarder to human eyes, and reflecting the first linearly polarized light emitted by the second phase retarder to the human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into first linearly polarized light;

the implementation mode is three:

the light emitted by the display element is first linearly polarized light;

the phase retarder includes: a first phase retarder located on one side of the polarization splitting element in a first direction;

the reflective element, comprising: a first reflecting element located on one side of the polarization splitting element in a first direction;

the polarization beam splitting element is used for reflecting the first linearly polarized light to the first phase retarder and transmitting the second linearly polarized light emitted by the first phase retarder to human eyes;

the first phase delay piece is used for converting the first linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the first reflecting element into second linearly polarized light;

the implementation mode is four:

the light emitted by the display element is second linearly polarized light;

the phase retarder includes: a second phase retarder on one side of the polarization splitting element in the second direction;

the reflective element, comprising: a second reflecting element located on one side of the polarization splitting element in the second direction; the second direction is a different direction from the first direction;

the polarization beam splitting element is used for transmitting the second linearly polarized light to the second phase retarder and reflecting the first linearly polarized light emitted by the second phase retarder to human eyes;

the second phase delay piece is used for converting the second linearly polarized light emitted by the polarization light splitting element into circularly polarized light and converting the circularly polarized light reflected by the second reflecting element into the first linearly polarized light.

2. The light field display device according to claim 1, wherein the first reflective element is a transflective element.

3. The light field display device according to claim 1, wherein the focus adjustment element comprises: a first liquid crystal layer and a second liquid crystal layer which are arranged in a stacked manner;

the initial orientations of the liquid crystals in the first liquid crystal layer and the second liquid crystal layer are orthogonal to each other.

4. The light field display device according to claim 1, wherein the gaze tracking element comprises: an infrared transmitter and an infrared receiver.

5. A display method of a light field display device according to any one of claims 1 to 4, comprising:

the sight tracking element detects three-dimensional position information of a human eye fixation point;

the system control element controls the image rendering element to render the display image according to a set time sequence according to the three-dimensional position information obtained by the sight tracking element, so that the display image accords with the visual effect of a human eye focusing plane;

the system control element controls the focal length adjusting element to adjust the focal length according to a set time sequence; the total duration of the set time sequence corresponding to each display period is less than the refreshing time of human eyes;

the display element emits light rays carrying image information of the rendered display image.

Images