A projection display method, device and readable storage medium

Abstract

The application discloses a projection display method and device and a readable storage medium, the projection display device comprises a light source and a scanning display device, the method comprises the following steps: reordering a to-be-displayed image according to a scanning time sequence of the scanning display device, the reordered data comprising pixel data of each pixel in the to-be-displayed image; outputting the reordered pixel data according to an image output rate and controlling the light source to be lighted; and driving the scanning display device to project and display light output by the light source according to a scanning period matched with the image output rate. The above scheme is used for solving the technical problem of poor pixel uniformity in the prior art, i.e., a laser scanning projection technology based on Lissajous scanning.

Description

Technical Field

[0001] This invention relates to the field of projection display, and more particularly to a projection display method, apparatus, and readable storage medium. Background Technology

[0002] The imaging principle of scanning projection technology is to modulate the light corresponding to each pixel of the image to be displayed by a light source, and then drive the scanning fiber or the scanning mirror of MEMS (Microelectro Mechanical Systems) to scan and output the light corresponding to each pixel, thereby projecting the light corresponding to each pixel of the image to be displayed onto the projection screen one by one to form a projected image.

[0003] In traditional display technologies, the pixels on a monitor are of uniform size, with each row and column of pixels arranged neatly, making it easy to control the pixel uniformity of the entire display. However, systems based on laser scanning projection rely on the duration of laser illumination and the trajectory of the laser spot to control pixel position and size. Using a Lissajous curve as an example, due to varying scanning speeds, the laser spot moves slower at the edges of the scan trajectory and faster near the center. Furthermore, the scan trajectory is denser at the edges compared to the center. Due to the inherent characteristics of the Lissajous curve, achieving pixel uniformity is extremely difficult.

[0004] It is evident that current laser scanning projection technology based on Lissajous scanning suffers from poor pixel uniformity. Summary of the Invention

[0005] The purpose of this invention is to provide a projection display method, apparatus, and readable storage medium to solve the technical problem of poor pixel uniformity in existing laser scanning projection technology based on Lissajous scanning.

[0006] To achieve the above-mentioned objective, a first aspect of the present invention provides a projection display method applied in a projection display device, the projection display device including a light source and a scanning display device, the method comprising:

[0007] The images to be displayed are reordered according to the scanning time sequence of the scanning display device, and the reordered data includes the pixel data of each pixel in the images to be displayed;

[0008] The reordered pixel data is output according to the image output rate to control the illumination of the light source;

[0009] The scanning display device is driven to project and display the light output from the light source according to a scanning cycle that matches the image output rate.

[0010] Optionally, the scanning cycle matching the image output rate satisfies the condition that the half-cycle time of the scanning display device in both the X and Y directions is an integer multiple of the pixel output time interval; wherein, the pixel output time interval refers to the time interval between two adjacent pixels output at the image output rate.

[0011] Optionally, the reordered pixel data is output according to the image output rate to control the illumination of the light source, including:

[0012] When dividing the pixel output time of all pixels in the image to be displayed, the division is carried out using an integer multiple of the pixel output time interval, and the time with the smallest error compared with the equidistant division is selected as the boundary of the pixel output time.

[0013] Based on the pixel data of each pixel in the image to be displayed and the output time of the divided pixels, the reordered pixel data is output to control the light source to be lit.

[0014] Optionally, the method further includes:

[0015] The brightness of each reordered pixel is adjusted based on the total scan time and the number of times the trajectory passes through each pixel.

[0016] A second aspect of the present invention provides a projection display device, comprising: a light source, a scanning display device, and a processor; the processor includes an image sorting module, a light source driving module, and a scanning device driving module;

[0017] The image sorting module is used to reorder the images to be displayed according to the scanning time order of the scanning display device. The reordered data includes the pixel data of each pixel in the image to be displayed.

[0018] The light source driving module is used to output reordered pixel data according to the image output rate and control the light source to be lit.

[0019] The scanning device driving module is used to drive the scanning display device to project and display the light output by the light source according to a scanning cycle that matches the image output rate.

[0020] Optionally, the scanning cycle matching the image output rate satisfies the condition that the half-cycle time of the scanning display device in both the X and Y directions is an integer multiple of the pixel output time interval; wherein, the pixel output time interval refers to the time interval between two adjacent pixels output at the image output rate.

[0021] Optionally, the light source driving module is used to divide the pixel output time of all pixels in the image to be displayed by using an integer multiple of the pixel output time interval, and select the time with the smallest error compared with the equidistant division as the boundary of the pixel output time when dividing the pixel output time.

[0022] Based on the pixel data of each pixel in the image to be displayed and the output time of the divided pixels, the reordered pixel data is output to control the light source to be lit.

[0023] Optionally, the processor further includes a brightness processing module, which is used to adjust the brightness of each reordered pixel data according to the total scanning time and the number of times the trajectory passes for each pixel.

[0024] A third aspect of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0025] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0026] In this embodiment of the invention, the image to be displayed is reordered according to the scanning time sequence of the scanning display device. The reordered data includes pixel data for each pixel in the image to be displayed. The reordered pixel data is output according to the image output rate, and the light source is controlled to be lit. The scanning display device is driven to project the light output by the light source according to a scanning cycle matched with the image output rate. By matching the scanning cycle of the scanning display device with the image output rate, the pixel display edges of each row and column can be aligned, and jagged edges will not appear on the pixel edges. This alleviates the technical problem of poor pixel uniformity in existing laser scanning projection technology based on Lissajous scanning, and improves pixel uniformity and display effect. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0028] Figure 1 This is a schematic diagram of the structure of a projection display device provided in an embodiment of the present invention;

[0029] Figure 2 A flowchart of the projection display method provided in an embodiment of the present invention;

[0030] Figures 3-4 A schematic diagram of a Lissajous curve provided for an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of an embodiment of the present invention, showing a pixel grid divided at equal intervals.

[0032] Figure 6 This is a schematic diagram illustrating the division of the pixel grid according to integer multiples of the pixel output time interval, as provided in an embodiment of the present invention.

[0033] Figure 7 A schematic diagram of pixel boundaries depicted in chronological order according to a trajectory, provided for an embodiment of the present invention;

[0034] Figure 8 A schematic diagram of an image to be displayed according to an embodiment of the present invention;

[0035] Figure 9A This is a diagram showing the effect of a Lissajous scanned image output according to the projection display method in this embodiment of the invention.

[0036] Figure 9B This is an image output effect diagram showing the pixel edges not being aligned, provided in an embodiment of the present invention.

[0037] Figure 10 A block diagram of a processor provided in an embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a projection display device 100 provided in an embodiment of the present invention. The device includes a light source 101, a scanning display device 102, and a processor 103.

[0040] The processor 103 can be a graphics processing unit (GPU), a central processing unit (CPU), or other chips or circuits with control and image processing functions, without being specifically limited here.

[0041] The processor 103 can control the light source 101 to modulate according to the image data to be displayed. In this embodiment of the invention, the light source 101 can be an RGB three-color laser group. The laser group contains multiple monochromatic lasers, each emitting a beam of a different color.

[0042] Then, the processor 103 controls the scanning display device 102 to scan according to a Lissajous motion pattern, thereby projecting the light output from the light source 101 to form a projected image. The scanning display device 102 can be a fiber optic scanning display device or a MEMS scanning device; this invention does not limit its application to either.

[0043] like Figure 2 As shown, Figure 2 A flowchart of a projection display method provided in an embodiment of the present invention, the method comprising the following steps.

[0044] Step 201: Reorder the images to be displayed according to the scanning time sequence of the scanning display device. The reordered data includes the pixel data of each pixel in the images to be displayed.

[0045] Since adjacent pixels on the Lissajous scan path may be located in different rows of the image to be displayed when displaying an image according to the scanning time sequence of the display device, it is necessary to reorder the pixels in the image to be displayed according to the Lissajous scan path.

[0046] Step 202: Output the reordered pixel data according to the image output rate, and control the light source to light up.

[0047] In this embodiment of the invention, an appropriate image output rate (i.e., image output sampling rate) can be selected based on the display resolution of the image to be displayed, the frame rate, the characteristics of the image output DAC device, and the performance of the light source.

[0048] Step 203: Drive the scanning display device to project and display the light output by the light source according to a scanning cycle that matches the image output rate.

[0049] In this embodiment of the invention, by selecting an appropriate image output rate and coordinating with the scanning display device driver, the image output can always be aligned in the pixel boundary direction, avoiding jagged edges at the pixel edges when displaying the image, which would seriously affect the display effect. This ensures that the edges of each row of pixels and each column of pixels are aligned, thereby guaranteeing the imaging quality.

[0050] Next, the projection display method in the embodiments of the present invention will be described in light of the characteristics of Lissajous scanning trajectories and the division of pixel boundaries.

[0051] Lissajous motion can be decomposed into simple harmonic motions in the X and Y directions. Assuming the frequency ratio in the X and Y directions is N / M, where M and N are two integers with no common divisor other than 1, then 2*M and 2*N represent the number of intersection points between a straight line drawn in the X and Y directions and the trajectory, respectively. The number of intersection points reflects the trajectory density; a denser trajectory allows for the display of more pixels. The Lissajous curve functions in the two directions are as follows:

[0052] x(t) = cos(2*pi*fx*t + Фx);

[0053] y(t) = cos(2*pi*fy*t + Фy);

[0054] Where fx / fy = N / M.

[0055] When Φx = Φy = k * 2 * pi (k is an integer), each trajectory of the Lissajous curve is traversed twice within one period, meaning each position on the trajectory is scanned twice. At this point, the intersection network formed by the trajectories is the sparsest. To make the Lissajous curve form a closed, symmetrical, and densest intersection network (beneficial for displaying more pixels), the phase difference of the curve needs to be adjusted so that Φx = ±i * pi / 2 + k1 * 2 * pi (i ≠ 0, k1 is an integer) and Φy = ±j * pi / 2 + k2 * 2 * pi (j ≠ 0, k2 is an integer). For example, when fx / fy = 7 / 8, the Lissajous curves when Φx = 0, Φy = 0 and Φx = pi / 2, Φy = pi / 2 are respectively as shown below. Figure 3 and Figure 4 As shown.

[0056] exist Figure 4 When dividing pixels along such a trajectory, for example, to display an 8x7 image, the horizontal and vertical axes are divided into 8 and 7 equal pixels respectively, using equal distances. Figure 5 As shown in the attached diagram (different colors are used to represent Lissajous curves and pixel grids for easy distinction), displaying the content of each pixel within its trajectory allows for the creation of an 8x7 image.

[0057] Since the Lissajous scanning trajectory undergoes simple harmonic motion in both the X and Y directions, the motion is not uniform and the time taken for the scanning trajectory within each pixel grid is not equal. The scanning trajectory takes a long time in some pixel grids and a short time in others. In order to make the image brightness uniform, it is necessary to adjust the brightness of the corresponding pixels in the pixel grids where the trajectory takes a long time and passes through many times.

[0058] To ensure that each row and column of pixels are aligned at the edges during display, the image output rate needs to be controlled so that the output sampling points are accurately located at the pixel boundaries. Otherwise, the pixel display edges will not be aligned, resulting in jagged edges and poor display quality.

[0059] In this embodiment of the invention, when selecting a suitable image output rate, a higher image output clock frequency can be chosen based on the performance of the light source used, i.e., the image output rate (outputting at equal time intervals, assuming the pixel output time interval or period is t0). This clock is used as the clock source for the scan drive signal, ensuring that the half-cycles of the output scan drive signal in the X and Y directions are integer multiples of t0. For example: t0 = 10 ns, the half-cycles in the X and Y directions are 3264*t0 and 3066*t0 respectively, then fx ≈ 15318.63 Hz, fy ≈ 16307.89 Hz. FPS stands for frame rate, which is the number of frames transmitted per second.

[0060] In this embodiment of the invention, since the image output DAC device used has its own fixed output rate (i.e., outputting at equal time intervals, assuming the pixel output time interval is t0), if the pixel grid is divided at equal distances, the distance and time are not linearly related due to the simple harmonic motion in the X and Y directions. Therefore, dividing the pixel grid at equal distances will prevent the image output sampling points from falling on the pixel grid boundaries, resulting in jagged edges on the pixel display and severely affecting the image display quality. To avoid this phenomenon, in this embodiment of the invention, the pixel grid is not divided at equal distances, but rather divided using integer multiples of t0, and the moment with the smallest error is selected as the boundary of the pixel grid. In this way, the pixel grid can be re-divided to obtain... Figure 6 The pixel grid division method is shown. The moment with the smallest error refers to the moment with the smallest error compared to the equidistant division.

[0061] In this diagram, green represents the ideal pixel grid boundary lines, divided at equal intervals, while black represents the pixel grid boundaries, divided in multiples of t0. While dividing the grid in multiples of t0 introduces some error in pixel size, it ensures that the output sampling points fall on the pixel grid boundaries during image display, avoiding jagged edges. To achieve this, the half-cycle times in both the X and Y directions must be integer multiples of the pixel output time interval t0. A half-cycle time is half of a cycle. It should be noted that when the grid division error is small, its impact on image display is almost negligible.

[0062] In this embodiment of the invention, the example described above, where t0 = 10 ns and the half-periods in the X and Y directions are 3264*t0 and 3066*t0 respectively, will be used for illustration. Figure 7 As shown, in Figure 7 The image depicts the pixel boundaries of the first few pixels in chronological order. Yellow sampling points represent the sampling points of the entire trajectory at image output time intervals t0. Green lines represent the boundary lines of evenly divided pixels, and black lines represent the actual boundary lines of the closest evenly divided pixels. Adjacent pixels are represented by different colors. The red, green, and blue color sampling points are examples of the sampling output positions of the first few pixels. It can be seen that the start and end of each pixel are on the boundary of the current actual pixel (black line), ensuring that the output image is aligned with pixel boundaries. The time intervals and pixel coordinates are as follows (taking a resolution of 640x480 as an example, 1-17 represent adjacent pixels in chronological order).

[0063] 1,0*t0~82*t0:(1,640)

[0064] 2,82*t0~92*t0:(1,639)

[0065] 3,92*t0~116*t0: (2,639)

[0066] 4,116*t0~129*t0: (2,638)

[0067] 5,129*t0~142*t0: (3,638)

[0068] 6,142*t0~157*t0: (3,637)

[0069] 7,157*t0~164*t0: (4,637)

[0070] 8,164*t0~181*t0: (4,636)

[0071] 9,181*t0~184*t0: (5,636)

[0072] 10,184*t0~202*t0: (5,635)

[0073] 11,202*t0~203*t0: (5,634)

[0074] 12,203*t0~218*t0: (6,634)

[0075] 13,218*t0~222*t0: (6,633)

[0076] 14,222*t0~233*t0: (7,633)

[0077] 15,233*t0~239*t0: (7,632)

[0078] 16,239*t0~247*t0: (8,632)

[0079] 17,247*t0~256*t0: (8,631)

[0080] Next, we will use a simulation of a 64x48 image displayed with N=55 and M=64 as an example to illustrate this. Figure 8 The image shown is the one to be displayed. Assume the stroke width of the letter E is 2 pixels, and the spacing between the strokes is also 2 pixels. Figure 9A The image output by the projection display method according to the embodiments of the present invention is a Lissajous scan display image, in which the relationship between the displayed image and the pixel grid is clearly shown. Figure 9A As can be seen, because the image output sampling position is accurately located at the pixel display boundary, the pixel edges are aligned. However, if the pixel boundary lines are divided evenly at equal intervals, the image output sampling points cannot fall on the pixel grid boundaries, resulting in jagged pixel display edges, severely affecting image display quality. Figure 9B The image shown is an output image where pixel edges cannot be aligned.

[0081] Based on the same inventive concept, embodiments of the present invention also provide a processor 1000, such as... Figure 10 As shown, it includes an image sorting module 1001, a light source driving module 1002, and a scanning device driving module 1003; the image sorting module 1001 is used to sort the images to be displayed according to the scanning time sequence of the scanning display device.

[0082] The data is reordered, and the reordered data includes the pixel data of each pixel in the image to be displayed; the light source driving module 1002 is used to output the reordered pixel data according to the image output rate and control the light source to be lit; the scanning device driving module 1003 is used to drive the scanning display device to project and display the light output by the light source according to a scanning cycle that matches the image output rate.

[0083] The processor 1000 also includes an image receiving module, static random access memory (SRAM), a brightness processing module, and a first-in-first-out (FIFO) buffer. The image receiving module receives the image to be displayed and stores it in the SRAM for buffering; the image sorting module 1001 rearranges the images according to their scan time order and outputs them to the FIFO buffer; the brightness processing module performs brightness weighting processing on the data from each rearranged output based on the total scan time of each pixel to ensure consistent brightness for each pixel; the light source driving module 1002 outputs the data from the FIFO buffer to control the light source to illuminate; and the scanning device driving module 1003 drives the motion of the scanning display device.

[0084] This invention also provides a computer-readable storage medium including program instructions that, when executed by a processor, implement the steps of the projection display method described above. For example, the computer-readable storage medium can be a memory, and the program instructions can be executed by the processor of a projection display device to complete the projection display method described above.

[0085] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0086] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0087] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A projection display method, characterized in that, Applied in a projection display device, the projection display device including a light source and a scanning display device, the method includes: The images to be displayed are reordered according to the scanning time sequence of the scanning display device, and the reordered data includes the pixel data of each pixel in the images to be displayed; When dividing the pixel output time of all pixels in the image to be displayed, the division is carried out using an integer multiple of the pixel output time interval, and the time with the smallest error between the pixels obtained by dividing the image at equal distances is selected as the boundary of the pixel output time; wherein, the pixel output time interval refers to the time interval between two adjacent pixels at the image output rate. Based on the pixel data of each pixel in the image to be displayed and the output time of the divided pixels, the reordered pixel data is output to control the light source to be lit; The scanning display device is driven to perform Lissajous scanning according to a scanning cycle that matches the image output rate, so as to project and display the light output from the light source.

2. The method as described in claim 1, characterized in that, The scanning cycle that matches the image output rate satisfies the condition that the half-cycle time of the scanning display device in both the X and Y directions is an integer multiple of the pixel output time interval.

3. The method as described in claim 1, characterized in that, The method further includes: The brightness of each reordered pixel is adjusted based on the total scan time and the number of times the trajectory passes through each pixel.

4. A projection display device, characterized in that, include: A light source, a scanning display device, and a processor; the processor includes an image sorting module, a light source driving module, and a scanning device driving module. The image sorting module is used to reorder the images to be displayed according to the scanning time order of the scanning display device. The reordered data includes the pixel data of each pixel in the image to be displayed. The light source driving module is used to divide the pixel output time of all pixels in the image to be displayed by using an integer multiple of the pixel output time interval, and to select the time with the smallest error between the pixels obtained by dividing the image at equal distances as the boundary of the pixel output time. The light source is controlled to be lit based on the pixel data of each pixel in the image to be displayed and the reordered pixel data after the pixel output time is divided; wherein, the pixel output time interval refers to the time interval between two adjacent pixels at the image output rate; The scanning device driving module is used to drive the scanning display device to perform Lissajous scanning according to a scanning cycle that matches the image output rate, so as to project and display the light output by the light source.

5. The apparatus as described in claim 4, characterized in that, The scanning cycle that matches the image output rate satisfies the condition that the half-cycle time of the scanning display device in both the X and Y directions is an integer multiple of the pixel output time interval.

6. The apparatus as claimed in claim 4, characterized in that, The processor also includes a brightness processing module, which is used to adjust the brightness of each reordered pixel data according to the total scanning time and the number of times the trajectory passes for each pixel.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method described in any one of claims 1-3.

Images