CN106773082A - A kind of method for weakening Morie fringe in bore hole 3D directive property back light systems - Google Patents

Abstract

The invention provides a method for weakening moiré fringes in a naked-eye 3D directional backlight system, and calculates and draws the moiré fringes generated on the LCD liquid crystal screen under different angles, distances and period ratios between the Fresnel lens group and the LCD liquid crystal screen ; Find the optimal value of the distance and angle between the Fresnel lens group and the LCD screen in the Moore fringe visual contrast distribution diagram generated by the periodic information of the Fresnel lens group and the LCD liquid crystal screen in the naked-eye 3D directional backlight system ; Construct a 3D directional backlight system according to the optimal value of the distance and angle between the found Fresnel lens group and the LCD screen. The present invention weakens moiré fringes without affecting the visual enjoyment of the naked-eye 3D system, and can greatly improve the quality of the visual sensory view.

Description

A method for weakening moiré fringes in a naked-eye 3D directional backlight system

technical field

The invention relates to the field of naked-eye 3D display systems, and more particularly, relates to a method for weakening moiré fringes in a naked-eye 3D directional backlight system.

Background technique

Moiré fringes are usually produced when two or more periodic structures are superimposed, which is an optical geometric effect of periodic structures. The moire effect will cause disturbing stripes to appear on the original image, interfere with the display of the image, and cause the image to be distorted in graphics and color.

In the naked-eye 3D system, the main components of the model include backlight, Fresnel lens group, LCD liquid crystal screen, and viewpoint. Different pictures projected by different backlight combinations reach different positions in the viewing area to achieve the naked-eye 3D effect. Among them, the superposition of the approximately periodically arranged Fresnel lens group and the LCD screen with periodically arranged pixels will cause more obvious moiré fringes to appear in some areas of the LCD screen, which will affect the image quality and reduce viewing experience. This problem occurs in many display fields. When shooting with a digital camera, if there is a periodic structure with a relatively similar resolution on the color filter of the image sensor, moiré fringes will appear obviously. In the 3D naked-eye system, the moiré fringes are more obvious. In the naked-eye 3D system based on the contour Fresnel lens, there will be obvious moiré fringes in the middle of the Fresnel lens group, which seriously affects the visual perception. Therefore, weakening the moiré fringe effect floating on the LCD screen has become an important task in the naked-eye 3D display system.

At present, the main method to weaken the Moiré fringe effect is to destroy the periodic structure of the system, which can significantly weaken the Moiré effect caused by the superposition of periodic structures. However, in some naked-eye 3D display systems, the structure of the Fresnel lens group is an important factor for realizing naked-eye 3D, and its periodic structure cannot be changed, and the use of non-periodically arranged LCD screens, which are rare in the market, is not conducive to Commercial applications of glasses-free 3D.

Contents of the invention

In order to overcome at least one defect described in the above-mentioned prior art, the present invention provides a method for weakening moiré fringes in a naked-eye 3D directional backlight system. While not affecting the visual enjoyment of the 3D directional backlight system, the moiré fringes are reduced. Large attenuation can drastically improve the quality of the visual sensory view.

In order to solve the problems of the technologies described above, the technical solution of the present invention is as follows:

A method for weakening moiré fringes in a naked-eye 3D directional backlight system, the naked-eye 3D directional backlight system comprising a backlight light source, a Fresnel lens group, an LCD liquid crystal screen and a virtual receiver arranged in sequence, comprising the following steps:

S1: Light up the backlight source, the backlight source emits in units of photons in all directions, the photons hit the sub-pixel grating of the LCD liquid crystal screen through the Fresnel lens group, are divided into different colors, and then are located in the virtual receiver located in the viewing area Reception: Fresnel lens can be regarded as a kind of quasi-periodically segmented grating, and each unit in the LCD liquid crystal screen can be regarded as a series of superposition of periodic sub-gratings transmitted by different colors.

S2: Remove the virtual receiver in the viewing area, directly analyze the distribution of photons hitting the LCD screen, adjust the distance range and angle range between the LCD screen and the lens, and simulate photons hitting one of the three primary color sub-pixel gratings on the LCD screen Dimensional brightness distribution;

S3: Calculate the moiré fringes produced by the Fresnel lens group and the LCD liquid crystal screen at different angles and period ratios on the LCD liquid crystal screen and draw the graph;

S4: Find the optimal distance and angle between the Fresnel lens group and the LCD screen in the moiré fringe visual contrast distribution diagram generated by the periodic information of the Fresnel lens group and the LCD liquid crystal screen in the naked-eye 3D directional backlight system value;

S5: Construct a 3D directional backlight system according to the found optimal values of the distance and angle between the Fresnel lens group and the LCD screen. In order to determine the relative positions of the backlight light source, the Fresnel lens group and the LCD screen, a naked-eye 3D directional backlight display system that can effectively eliminate the moiré effect is designed.

In a preferred solution, the display layer of the LCD liquid crystal screen is divided into several units, and each unit can be adjusted in brightness with the three primary colors of red, green and blue, so as to display any color. Different color distributions do not interfere with each other, and each unit can be regarded as a monochromatic quasi-periodic sub-grating structure.

In a preferred solution, the Fresnel lens group and the LCD liquid crystal screen do not need to be strictly matched, and the optimal distance between them is the minimum distance that can eliminate moiré fringes. For the equal-height Fresnel lens system, the optimal value is 40mm. As the distance increases, the moiré fringe tends to weaken, but because the distance between the Fresnel lens group of the naked-eye 3D directional backlight system and the LCD screen is too far, the viewing angle of the display system will be limited, and the thickness of the system will increase. The crosstalk rate increases, so the separation distance should be controlled as much as possible under the premise that moiré fringes are invisible.

In a preferred solution, the backlight source is arranged on the incident surface side of the Fresnel lens array, the backlight is composed of several independent linear light-emitting units, and the linear light-emitting units are combined to form the first light-emitting unit and the first light-emitting unit. The second light-emitting unit, each light-emitting unit corresponds to a viewing area at the front end of the entire device, the first light-emitting unit corresponds to the first viewing area, and the second light-emitting unit corresponds to the second viewing area.

In a preferred solution, the Fresnel lens group is spliced by several Fresnel lens units, each Fresnel lens unit corresponds to a linear light-emitting unit, and the Fresnel lens unit can focus on the corresponding The light emitted by the linear light-emitting unit forms a quasi-periodic focused light.

Compared with the prior art, the beneficial effect of the technical solution of the present invention is: the present invention provides a method for weakening moiré fringes in a naked-eye 3D directional backlight system, and calculates the Fresnel lens group and the LCD liquid crystal screen at different angles and periods. In contrast, the moiré fringes generated by the LCD liquid crystal screen are drawn; in the naked-eye 3D directional backlight system, the Fresnel lens group and the periodic information of the LCD liquid crystal screen generate the moiré fringe visual contrast distribution diagram, and find out the Fresnel The optimal value of the distance and angle between the Fresnel lens group and the LCD screen; according to the found optimal value of the distance and angle between the Fresnel lens group and the LCD screen, a 3D directional backlight system is constructed. Since the LCD liquid crystal screen is a high-transparency structure with a low scattering rate, it is not necessary to strictly align the angle and distance of the Fresnel lens group to have a 3D display effect, so it can be adjusted by adjusting a certain angle and distance. Reduce the generation of moiré fringes without reducing the effect of the 3D display system. The invention weakens moiré fringes without affecting the visual enjoyment of the naked-eye 3D system, and can greatly improve the quality of the visual sensory view.

Description of drawings

FIG. 1 is a schematic diagram of the naked-eye 3D directional backlight system in Embodiment 1.

Fig. 2 is a basis diagram of the Fresnel lens group regarded as a periodic grating in the present invention.

FIG. 3 is a raster diagram showing that any of the three primary colors of the LCD screen is regarded as a sub-pixel raster in the present invention.

FIG. 4 is a structural diagram of the optical program simulation of the naked-eye 3D directional backlight system in Embodiment 2. FIG.

FIG. 5 is a model diagram generated by the Moore fringe experiment of the naked-eye 3D directional backlight system in Example 3. FIG.

Fig. 6 is a distribution diagram of the one-dimensional light intensity amplitude position distribution of moiré fringes under different distances between the optical film layer and the LCD liquid crystal screen in the naked-eye 3D system.

FIG. 7 is a graph showing the relationship between the sensitivity contrast and the distance increase in the naked-eye 3D system.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

Fig. 1 is a schematic diagram of a naked-eye 3D directional backlight system, including a backlight source 10, a Fresnel lens group 11, an LCD liquid crystal screen 12 (periodically blocking the grating), and a virtual receiver 13 (simulating the viewing area of human eyes). The combination of Niel lens group and LCD liquid crystal screen can realize 3D display effect. The directional backlight is to select the arrangement of turning on and off of the backlight to switch the viewing area of the naked-eye 3D display. For the sake of simulation simplicity, choose to turn on the two backlights facing the middle of the Fresnel lens group.

An analysis example of moiré fringes in the naked-eye 3D directional backlight system given in Figure 2-3 mainly includes the following principles and methods:

1. The grating has a typical periodic structure. Two overlapping periodic gratings can present typical moiré fringes. This phenomenon can be explained by the principle of shading and shading—that is, from the perspective of geometric optics.

2. Due to the structure of the Fresnel lens, the backlight can be unitized into a photon number to perform geometrical optics incident and exit simulation through the Fresnel lens. When the simulated photon number hits the LCD screen, it can perform one-dimensional Statistical photon count results.

It can be seen from the statistical results of the one-dimensional photon number that the light intensity after passing through the Fresnel lens group presents a quasi-periodic distribution of alternating bright and dark. Therefore, the Fresnel lens can be simplified into a grating structure, as shown in Figure 2.

Image caption for Figure 2:

(1) Normalize the maximum value of the one-dimensional statistical data of the number of photons to form a quasi-periodic fluctuating distribution structure;

(2) Convert photon count statistics into a pseudo-two-dimensional light intensity gradient statistical image;

(3) According to the boundary with the limit of 20% lower than the maximum light intensity, the quasi-periodic distribution of light intensity in alternating light and dark can be obtained, which can be regarded as a quasi-periodic grating structure.

3. For the naked-eye 3D system, the LCD liquid crystal screen has the properties of low scattering rate and high transmittance. The microstructure of the three primary color sub-pixels is shown in FIG. 3 .

Figure 3 image description:

(1) The red, green and blue primary color microstructure stripes do not intersect each other and change periodically;

(2) The periodic influence of one primary color on the other two primary colors is weak and can be approximately ignored;

(3) The grayscale of a single primary color can be regarded as the sub-pixels of the same color are periodically arranged into sub-gratings;

(4) The LCD pixel is regarded as three overlapping sub-gratings with equal periods;

According to the analysis of the one-dimensional photon distribution of the linear Fresnel lens film layer in the polarizing device in (1), it has a gradually changing periodic structure. Therefore, it can be simplified into a quasi-periodic structure, which is called Fresnel lens simplified grating.

The LCD liquid crystal screen is an ordinary display screen with a periodic pixel array. The sub-pixels of the same color form a grating, which is called a sub-pixel grating. The region can be regarded as two periodic gratings superimposed to form obvious moiré fringes.

Example 2:

As shown in Figure 4, this embodiment provides a method for reducing moiré fringes in a naked-eye 3D directional backlight system:

1. Carry out the simulation model according to the image in Figure 4, and the image description:

(1) No. 20 is a controllable switch backlight light source, and the backlight is a straight plane for the convenience of fitting;

(2) No. 21 is a Fresnel lens group of equal height in a simple simulation 3D display system, and the Fresnel lens group of the polarizing device has a zigzag structure of equal height. Its film thickness is only 0.15mm, so the absorption loss due to the lens is negligible. Its focal length is 123.4cm, the refractive index of the substrate layer is 1.5, and the refractive index of the lens layer is 1.561;

(3) No. 22 is a sub-grating in which the three primary colors of the LCD screen do not overlap each other, and statistics are made on the moiré fringe distribution of the light hitting the plane;

(4) No. 23 is a virtual light source receiver, the viewing area is 4×4mm, and the center distance from the Z axis is P. Because it can be replaced by a high-definition camera in the experimental stage, it can be directly considered on the LCD screen and the center distance Z The axis is the statistics of the photon distribution at P;

2. In the process of simulating the Fresnel lens, only consider the photon arrangement characteristics when a group of backlight light sources enter the virtual light source receiver and pass through the LCD screen. The size of the viewing area on the LCD screen is also about 4× 4mm, the distance P from the center to the Z axis is 25mm. Set up the program to calculate the incident and exit conditions of photons, and simulate the one-dimensional distribution of photons in the viewing area after passing through the lens and the three-primary color sub-grating of the LCD liquid crystal screen within a certain range of position and speed.

3. On the LCD screen, the three primary colors are separated, and the matrix points are multiplied by one-dimensional normalized photon distribution to form a simulated image produced by bright and dark moiré fringes.

4. Adjust the parameters of the simulation program to control the angle between the polarizing device and the LCD screen to vary from 0 to 8 degrees, and the distance between the two periodic devices to be between 0 mm and 50 mm.

5. When the contrast of the moiré fringes drops to 30% or less of the original value, it is considered that the moiré fringes are eliminated. The minimum space separation distance for moiré fringe elimination is the optimal distance. For the lens system, the distance is 40 mm.

By adjusting the parameters and comparing different simulation results, it can be concluded that as the distance between the Fresnel lens and the LCD screen increases, the distribution of light intensity on the virtual receiver becomes more uniform, and the effect of moiré fringes becomes more uniform. getting weaker. According to the principle of linear propagation of light, increasing the distance between the Fresnel lens and the LCD liquid crystal screen is equivalent to increasing the period of the grating simplified by the virtual Fresnel lens group with a distance P from the LCD.

The method of light field calculation is used to simulate the light intensity distribution of moiré fringes, and a new moiré fringe analysis method is provided. The strength of moiré fringes can be judged more accurately through the difference between the maximum and minimum amplitudes.

Therefore, it can be seen that when the angle between the Fresnel lens and the LCD liquid crystal screen is 0 degrees, the farther the distance is, the weaker the contrast effect of Moore fringes is. Therefore, in this experimental simulation, the Fresnel lens and the LCD liquid crystal The two-period structure of the screen is almost invisible at a distance of 40mm. According to the experimental results, it can be known that the positional relationship between the Fresnel lens group and the LCD liquid crystal screen in the naked-eye 3D directional backlight system can weaken the Moire effect to the greatest extent.

Example 3:

As shown in Figure 5, this embodiment provides a method for reducing moiré fringes in a naked-eye 3D directional backlight system:

1. Carry out simulation according to the model of the image in Figure 5, the image description:

(1) No. 30 is a controllable switch backlight light source. For the convenience of the experiment, two backlight light sources facing the Fresnel lens can be turned on;

(2) Number 31 is a Fresnel lens group of equal height in a simple analog 3D display system, and the Fresnel lens group of the polarizing device has a zigzag structure of equal height. Its film thickness is only 0.15mm, so the absorption loss due to the lens is negligible. Its focal length is 123.4mm, the refractive index of the substrate layer is 1.5, and the refractive index of the lens layer is 1.561;

(3) No. 32 is an LCD liquid crystal screen with low scattering rate and high permeability;

(4) No. 33 is a virtual light source receiver, which can be replaced by a high-definition camera in the experimental stage, so it can directly observe the distribution of moiré fringes on the LCD screen;

2. The experiment shown in Figure 5 is a simple naked-eye 3D system directional backlight experiment, which is used to analyze the generation of moiré fringes. Turn on the middle of the backlight and turn off the rest, place a Fresnel lens at a specific angle and an LCD screen at a specific distance.

3. The photons hit on the plane of the LCD liquid crystal screen are arranged in a quasi-periodical arrangement of alternating bright and dark, superimposed on the three primary color sub-gratings on the LCD liquid crystal screen, and use high-definition in the viewing area when the distance from the Z axis P to the center is 25mm. Camera shooting, can get color moiré fringe pattern, so as to replace naked eye observation.

4. In Figure 5, the backlight light source passes through the periodic Fresnel lens group and the LCD screen, because the Fresnel lens can be tilted at a certain angle, thus forming a certain angle with the LCD screen. Adjust the parameters to control the angle between the polarizing device and the LCD liquid crystal screen to be 0, 2, 4, 6, 8 degrees and the distance between the two periodic devices to be between 0 mm and 50 mm.

5. According to the first 4 steps of Example 3, the software analyzes the light intensity contrast of the pictures taken in the experiment under different angles and distances of the parameters, and finds out the most suitable angle and distance in the experiment.

In step (4), the distance between the backlight light probe and the Fresnel lens is fixed in the naked-eye 3D vision system, and only the inclination angle of the Fresnel lens and the distance between the Fresnel lens and the LCD screen are changed to change the generated Moore. The strength and weakness of the streak effect.

In step (4), the observation method is to take pictures with a high-definition camera, and compare pictures in the range of an angle of 0 to 8 degrees and a distance of 0 mm to 50 mm.

In step (4), due to the error in the experimental process compared with the simulation effect, the distance adjustment range of the two periodic devices should be increased accordingly to see the change trend more clearly, so the distance is between 0mm and 50mm, step by step The speed is 5mm.

In step (5), fix each picture with a certain position as a reference point, draw a line in the direction of vertical moiré fringes through this position point, and use light intensity analysis software to conduct one-dimensional light intensity analysis, so as to obtain In practice, the light intensity contrast of moiré fringes at a fixed angle and a fixed distance.

In the obtained one-dimensional light intensity contrast, there is an obvious trigonometric function periodicity, and the difference between a certain maximum peak I _max and a minimum peak I _min is used as the light intensity amplitude difference to record it as the moiré fringe light intensity contrast Evaluation metrics.

Recording was carried out at different distances at the same angle, and the relationship between the light intensity amplitude difference and the distance was obtained, and the results are shown in Figure 6-7.

Image description for Figure 6-7:

(1) Fig. 6 is the obtained position distribution curve diagram of the amplitude at different distances from 0 to 50 mm in the viewing zone at a distance of 25 mm from the center of the Z axis;

(2) From the experimental results in Figure 7, it can be concluded by software simulation that as the distance increases, the amplitude difference between the maximum value and the minimum value will become smaller and smaller, that is, the moiré fringe will show a weakening trend. That is, Figure (b) is a comparison chart of the relative average strength θ of the sensitivity contrast of the moiré fringe effect at different distances;

Therefore, the distance between the two devices with the minimum contrast ratio of the moiré fringes is found, so as to weaken or even eliminate the moiré fringes. The recommended distance for the resulting low light intensity contrast is 40mm.

Claims (5)

1. a method for weakening moiré fringes in a naked-eye 3D directional backlight system, said naked-eye 3D directional backlight system comprising a backlight light source, a Fresnel lens group, an LCD liquid crystal screen and a virtual receiver arranged in sequence, characterized in that , including the following steps: S1: Light up the backlight source, the backlight source emits in units of photons in all directions, the photons hit the sub-pixel grating of the LCD liquid crystal screen through the Fresnel lens group, are divided into different colors, and then are located in the virtual receiver located in the viewing area take over; S2: Remove the virtual receiver in the viewing area, directly analyze the distribution of photons hitting the LCD screen, adjust the distance range and angle range between the LCD screen and the lens, and simulate photons hitting one of the three primary color sub-pixel gratings on the LCD screen Dimensional brightness distribution; S3: Calculate the moiré fringes produced by the Fresnel lens group and the LCD liquid crystal screen at different angles and period ratios on the LCD liquid crystal screen and draw the graph; S4: Find the optimal distance and angle between the Fresnel lens group and the LCD screen in the moiré fringe visual contrast distribution diagram generated by the periodic information of the Fresnel lens group and the LCD liquid crystal screen in the naked-eye 3D directional backlight system value; S5: Construct a 3D directional backlight system according to the found optimal values of the distance and angle between the Fresnel lens group and the LCD screen. 2. the method for weakening moiré fringes in the naked-eye 3D directional backlight system according to claim 1, is characterized in that, the display layer of described LCD liquid crystal screen is divided into several units, and each unit can use three primary colors of red, green and blue Adjust brightness to show any color. 3. The method for weakening moiré fringes in the naked-eye 3D directional backlight system according to claim 1, wherein the Fresnel lens group and the LCD liquid crystal screen do not need to be strictly matched, and the optimal value of the spacing distance can be The minimum separation distance for eliminating moiré fringes, for a constant-height Fresnel lens system, the optimal value is 40mm. 4. The method for weakening moiré fringes in the naked-eye 3D directional backlight system according to claim 1, wherein the backlight source is arranged on one side of the incident surface of the Fresnel lens array, and the backlight source consists of several independent lines Type light-emitting units spliced together, line-type light-emitting units are combined to form the first light-emitting unit and the second light-emitting unit, each light-emitting unit corresponds to a viewing area at the front end of the entire device, the first light-emitting unit corresponds to the first viewing area, and the second light-emitting unit corresponds to a viewing area. Lighting unit for second viewport. 5. The method for weakening moiré fringes in the naked-eye 3D directional backlight system according to claim 1, wherein the Fresnel lens group is spliced by several Fresnel lens units, and each Fresnel lens unit The lens unit corresponds to a linear light emitting unit, and the Fresnel lens unit can focus the light emitted by the corresponding linear light emitting unit to form a quasi-periodic focused light.