GB2550137A

GB2550137A - Method and apparatus for tiles light field display

Info

Publication number: GB2550137A
Application number: GB1608082.2A
Authority: GB
Inventors: Lu Min; Tan Baolin; Kang Jianghui; Ma Xiaoqi; Wu Yu
Original assignee: Shenzhen Yinglun Tech Ltd; Euro Electronics (uk) Ltd
Current assignee: Shenzhen Yinglun Tech Ltd; Euro Electronics (uk) Ltd
Priority date: 2016-05-09
Filing date: 2016-05-09
Publication date: 2017-11-15
Also published as: GB201608082D0

Abstract

A tiled light field display 1 is composed of small size light field displays 4 and a synchronous signal processing system. Preferably each small light field display is composed of a small flat panel and a microlens array 5. Preferably the display is assembled and aligned by displaying testing images composed of vertical and horizontal lines. Preferably the assembly and alignment starts at the first row and first column. Preferably the elemental images displayed are rendered based on the parallel movement of the small light field display.

Description

Method and Apparatus for Tiled Light Field Display Background

This invention relates to a tiled light field (LF) display apparatus. More particularly this present invention relates to a small size flat panel display screen, the corresponding microlens arrays, the alignment between the adjacent LF displays, and a synchronized signal processing system. A three-dimensional (3D) display can display a 3D scene to a viewer by conveying the perception of depth to him. A LF display composed of a flat panel and a microlens array is one type of 3D displays, which restructures a 3D scene through the microlens array by reproducing the 4D LF function of the original 3D scene in space. When a viewer watches a 3D scene produced by a LF display, both of eyes accommodate and converge to the same position which means there doesn’t exist the accommodation-vergence conflict.

Although a LF display can display a real 3D scene, the size, the cost and the 3D image quality of this display are limited by the fabrication of a microlens array. There are many suitable manufacturing techniques for producing a microlens array, such as reflow or resist-melting method, epitaxial growth method and 3D printing method. But the cost and the manufacture precision of a microlens array are limited by these techniques, which means that its cost increases quickly when the size is enlarged, while its manufacture precision, which has an important impact on the 3D image quality, is reduced at the same time. These problems become the constraint to the size and the cost of a LF display.

This present invention gives a solution of a large LF display by tiling small LF displays. Hence, there are several problems to solve to get a high quality large size LF display. The first problem is the alignment of adjacent LF displays. The second problem is the synchronization of 3D signals.

Statements of invention

The present invention provides a tiled LF display comprising anMxiV array of LF displays (named as sub-LF display). Here, M and N are the numbers of rows and columns, respectively. Each sub-LF display is composed of a small flat panel screen and a microlens array. In this invention, each sub-LF display is qualified, which means each of them is aligned, and each elemental image area is projected by its corresponding microlens lenslet.

As discussed before, two problems should be solved to get a tiled LF display. One is about the sub-LF displays assembly. The other is about the synchronization of image signals. During the stage of assembly, this invention will solve the following problems: 1) the alignment of adjacent sub-LF display at the horizontal direction, 2) the alignment of adjacent sub-LF display at the vertical direction, 3) the alignment of a whole column/row.

For the convenience of discussion, this present invention sets the top left point of the whole LF display as the origin point of the coordinate at the LF display plane, and sets the downwards direction and the right direction of the first sub-LF display as the positive directions of x-axis and y-axis. Here, the first sub-LF display is the top left one at the tiled LF display plane, and is described as (1,1) sub-LF display. In this invention, a sub-LF display on mth row and nth column can be marked as (m, ri) sub-LF display, where 1 <m < M and 1 < η < N.

The assembly of a tiled LF display is from the alignment of the (1,1) sub-LF display. Because each sub-LF display is qualified, it is supposed that each sub-LF display satisfies the requirement of design and the microlens array doesn’t have any rotation or parallel movement. To make sure that the (1,1) sub-LF display is placed at right direct without any rotation, the pixels at the centre of each lenslet in the first three rows display white colour. A camera placed within the field of view takes photos to check whether these white lines are horizontal or not. When these white lines are horizontal, the alignment of (1,1) sub-LF display finishes. Otherwise, the (1,1) sub-LF display is rotated slightly until these white lines are horizontal. Then, the (1,2) sub-LF display is placed by the (1,1) sub-LF display. The pixels at the centre of each lenslet in the first three rows display white colour as well. The (1,2) sub-LF display is fine-tuned until the white lines become the corresponding extended lines of the three white lines on the (1,1) sub-LF display. The assembly and alignment of the other sub-LF displays in the horizontal direction follows these steps.

When the first row of the tiled LF display is assembled, it starts to assemble and align the first column of the tiled LF display. All the pixels at the centre of each lenslet in the first three columns on each sub-LF display show white colour. The assembly and alignment starts from (2,1) sub-LF display to (Μ, 1) sub-LF display, which means (2,1) sub-LF display is fine-tuned until its white lines become the extended lines of the white lines on (1,1) sub-LF display, then the (3,1), ..., (M, 1) sub-LF displays are fine-tuned and aligned one by one.

Then the sub-LF displays on the second row ((2, n) sub-LF display) are assembled. All the pixels of (2,2) sub-LF display at the centre of each lenslet in the first three rows and first three columns display white colour. The (2,2) sub-LF display is fine-tuned vertically until the horizontal white lines become the corresponding extended lines of the (2,1) sub-LF display. Then it is fine-tuned horizontally until the vertical lines become the extended lines of the (1,2) sub-LF display. The other sub-LF displays ((2, n), 2 < η < N) on this row are assembled and aligned by these steps.

The sub-LF display (m, ri) (2 < m < M, 2 < η < N) can follow these steps: 1) assembling the (m,n) sub-LF display, 2) aligning the vertical position by the horizontal testing lines, 3) aligning the horizontal position by the vertical testing lines.

When all of the sub-LF displays are assembled and aligned one by one, the consistency of the tiled LF display is satisfied. The output elemental images should be re-arranged by the shape of the lenslet fragment at the edge of the microlens array and the gap between the adjacent screens. In this present invention, the lenslets at the edge of the microlens array may not be a whole lenslet but only a part of it. Hence, the content of elemental images along the edges of sub-LF displays should be adjusted, and this may affect the image content of the other elemental images on the display.

When the tiled LF display is assembled, the photos taken to align the sub-LF displays are employed to analyse the shapes of the lenslets along the edges and the gap between the adjacent screens. Here, the parameters of each microlens array, such as the lenslet arrangement, the focal length and the horizontal and vertical pitches of lenslet, are known as the design. According to the distances between two adjacent white dots at two sub-LF displays, the shapes of the lenslet fragment are detected, and the size of the gap between two screens is measured. Based on these data, the coordinate shift of each sub-LF plane is given. Then a new group of elemental images can be formed by resampling the original 3D scene.

In one embodiment, the horizontal and vertical gaps between the adjacent displays are bigger than the horizontal and vertical pitches of the microlens lenslet. These big gaps lead to the shifts of the elemental images, which means the pixels forming a 3D scene cannot be projected to the desired position. Here, this results in the image deformation.

In this case, the LF-display needs a new group of elemental images for each sub-LF display to eliminate the image deformation. This new group of elemental images can be produced by resampling the original 3D scene restructured in a virtual space.

Detailed Description of the Invention

An example tiled LF display of the present invention will now be described by referring to the accompanying figures in which:

Figure 1 is a schematic diagram of a tiled LF display comprising of 3 x 3 sub-LF displays;

Figure 2 is a schematic diagram of the arrangement of the microlens lenslets; Figure 3 is a schematic diagram of an elemental image and its corresponding lenslet;

Figure 4 is a schematic diagram of the testing image of the tiled LF display; Figure 5 is the working flow of the assembly and alignment of a tiled LF display;

Figure 6 is the working flow of the assembly and alignment of the (1,1) sub- LF display;

Figure 7 is a working flow of producing a new group of elemental images.

This present invention will be described in detail in relation to a tiled LF display 1 shown in Figure 1. In this embodiment, a tiled LF display 1 is composed of 3 x 3 sub-LF displays 4, and each sub-LF display 4 comprises a flat panel display 3 with a microlens array 2. The gap between the flat panel display 3 and the corresponding microlens array 2 is g, here g = f. / is the focal length of the microlens lenslet. As stated in the Statement, a specific sub-LF display 4 is named as (m, n) by its position on the tiled LF display 1. Hence, there are (1,1), (1,2) , ..., (2,3) and (3,3) sub-LF displays 4. A microlens array 2 is composed of / x J array lenslets 5, where / and J are the numbers of rows and columns, respectively.

There are different arrangements of the microlens lenslets 5, such as the orthogonal array, and the hexagonal array. Here, a hexagonal arrangement is employed and shown in Figure 2. In this figure, the diameter of a lenslet 5 is PL, the horizontal and vertical pitches of the microlens array are ^Lx and PLy5 respectively, and

A sample of an elemental image 6 and its corresponding lenslet 5 is shown in Figure 3. In this case, a lenslet 5 can cover 10 X 10 pixels 7, which means PL = 10p, and the pitch of an elemental image Pet is Pet = 10p. Here, the pitch of a pixel 7 is p.

Figure 4 shows the testing images on each sub-LF display 4. A camera 8 within the field of view takes photos which are sent to the computer to analyse the situation of each sub-LF display 4. The horizontal and vertical white lines are formed by the pixels at the centre of each lenslet 5 in the first three rows and columns of each sub-LF display 4, respectively.

The working flow to assemble and align this tiled LF display 1 is shown in Figure 5. The work starts from assembling and aligning the (1,1) sub-LF display 4. The working flow to align the (1,1) sub-LF display 4 is shown in Figure 6. Firstly, the (1,1) sub-LF display shows the horizontal testing lines shown in Figure 4. Then, a camera 8 takes photos to check whether these white lines are horizontal or not. If they are not horizontal, the (1,1) sub-LF display 4 will be fine-tuned until these lines are horizontal. Now the alignment of the (1,1) sub-LF display 4 is finished.

Then the (1,2) sub-LF display 4 is assembled and aligned by displaying the horizontal testing lines, taking photos and checking whether they are the horizontal extended lines of these horizontal testing lines on the (1,1) sub-LF display 4. When the testing lines satisfy the requirement, the alignment of (1,2) sub-LF display 4 is finished.

The assembly and alignment of the (1,3) sub-LF display 4 is same as the work done on the (1,2) sub-LF display 4. But the horizontal testing lines should be the horizontal extended lines of these horizontal testing lines on the (1,2) sub-LF display 4 in this case.

When the first row of the tiled LF display 1 has been aligned, the assembly and alignment of the (2,1) sub-LF display 4 will be done by showing the vertical testing lines on each sub-LF display 4. As shown in Figure 4, the (1,1) and (2,1) sub-LF displays 4 show the vertical testing lines. The (2,1) sub-LF display 4 is adjusted carefully until its vertical testing lines become the vertical extended lines on the (1,1) sub-LF display 4. Then the (3,1) sub-LF display 4 is assembled and aligned in the same way.

The rest of sub-LF displays 4 are assembled and aligned by both their horizontal and vertical testing lines. Firstly, the (2,2) sub-LF display 4 shows the horizontal testing lines. Then, the camera 8 takes photos to check the vertical position of this sub-LF display 4. When its horizontal testing lines become the horizontal extended lines of the (2,1) sub-LF display 4, the assembly and the alignment are finished. Now, the vertical testing lines are displayed on this sub-LF display to align the horizontal positon. Finally, when the vertical testing lines are the vertical extended lines of the (1,3) sub-LF display 4, this sub-LF display satisfies the assembly requirement. The (2,3), (3,2) and (3,3) sub-LF displays are assembled and aligned as the method stated in this paragraph.

When the assembly and alignment are finished, the testing image on the whole tiled LF display 1 is same as the pattern shown in Figure 4. This tiled LF display 1 is ready to restructure a 3D scene. Because this LF display 1 is a tiled display, there are black gaps between the adjacent sub-LF displays 4. Compared with a normal LF display, these gaps lead to the parallel movement of the elemental images 6, furtherly result in the potential deformation of a 3D scene. To avoid this deformation, the elemental images 6 to represent a 3D scene should be adjusted.

The working flow of rendering a new group of the elemental images 6 is shown in Figure 7. A 3D scene can be restructured in a virtual space by the original group of elemental images 6. The size of gap between the adjacent sub-LF display 4 can be measured by the gap between the horizontal/vertical testing lines on the adjacent sub-LF displays 4. The parallel movement of each sub-LF display 4, excluding the (1,1) sub-LF display 4, can be tested by this way. A new group of elemental images 6 for the tile LF display 1 can be rendered by the computer graphic techniques, and restructures a 3D scene for viewers.

Claims

Claims 1 A tiled light field display comprising an Μ x N array of small light field displays (M and N are the numbers of rows and columns, respectively), and an image signal rendering and transmission system which renders the corresponding elemental images and outputs synchronous signals. 2 A tiled light field display as claimed in claim 1, wherein a small light field display is composed of a small flat panel and a microlens array which has an / X J array lenslets ( / and J are the numbers of rows and columns, respectively). 3 A small light field display as claimed in claim 2, wherein the assembly and the alignment are done by displaying the testing images composed of the horizontal and vertical lines. 4 A tile light field display as claimed in claim 1, wherein the assembly and the alignment start from the first row and the first column, to the rest of part. 5 A tile light field display as claimed in claim 1, wherein the elemental images displayed are rendered based on the parallel movement of the small light field displays.