Front light microled for microdisplays

Abstract

The present invention discloses the development of a high-performing full-color microdisplay with low power consumption. In particular, the use of light modulation in microdisplays, polarizing beamsplitter, transparent structures and waveguides is disclosed. The light modulation image is used to improve the output image resolution. The present invention relates to an optical system as an emissive display.

Description

Front Light MicroLED for MicroDisplaysField of the invention

[0001] The present disclosure relates to developing high-performing microdisplays by combining liquid crystal or DLP (DMD) microdisplays and low-resolution microLED microdisplays. The present disclosure also relates to an optical system that can operate in two different modes of lighting and display.Summary[2] The present invention relates to a method to project an image from a microLED microdisplay (ML) into a light-modulating microdisplay (LM), the method comprising, having an ML display, having a LM display, and using a polarizing beamsplitter to project the image from the ML display into the LM display to improve a resolution.[3] The present invention relates to a method to project an image from a microLED microdisplay(ML) into a light-modulating microdisplay (LM), the method comprising, having an ML microdisplay, having a LM microdisplay and using a waveguide to project the image from the ML microdisplay into the LM microdisplay[4] The present invention relates to a method to run an optical system, the method comprising, having a display and a driving system, having pixels with MicroLEDs, having the pixels in the display, using drivers for each operation mode if the display pixels are passive and having an external driver providing a driving current.Brief description of the Drawings[5] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.[6] Figure 1 shows an embodiment of optical structure, allowing image from the microLED microdisplay to be projected into a light-modulating microdisplay and image with the improved resolution is output.[7] Figure 1A, and Figure IB show two examples of using PBS with microLED (ML) microdisplay and light-modulating microdisplay.[8] Figure 1C shows a related embodiment where the images pass through a transparent structure where the LM is put on the surface at an angle.[9] Figure 2 shows another related embodiment of an optical structure, allowing the image from an ML microdisplay to be projected onto an LM microdisplay. It shows a MicroLED backlight for light modulation microdisplays using waveguide.

[0010] Figure 3 shows an optical system supporting the embodiments described here with a display and a driving system.

[0011] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of an invention as defined by the appended claims.Detailed Description

[0012] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which the same numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.

[0013] The development of a high-performing full-color microdisplay with low power consumption is crucial for several applications, including augmented reality.

[0014] The present invention relates to the development of a high-performing full-color microdisplay with low power consumption, which is crucial for several applications, including augmented reality.

[0015] However, each technology has its limitations. Here, a low-resolution microLED microdisplay is developed, and the image from the microLED microdisplay is projected into a light modulation microdisplay. The light modulation microdisplay can be liquid crystal or (Digital Light processing) DLP. The low-resolution microLED microdisplay is a low-power display and produces images at low power consumption. The light modulation image is used to improve the output image’s resolution.

[0016] Here, the microLED microdisplay can produce a color image during each frame, and the light modulation display is used to improve the resolution of the full-color image. In another related embodiment, the microLED microdisplay creates images with different colors during different subframes, and the light-modulating microdisplay improves the image’s resolution for that color during each subframe.

[0017] Figure 1A, and Figure IB, show an embodiment of optical structure 100, allowing image 108 from the microLED microdisplay 104 to be projected into a light-modulating microdisplay 102 and image 110 with the improved resolution is output. In one related embodiment, a polarizing beamsplitter (PBS) 106 is used to project the image from the microLED microdisplay into the light-modulating microdisplay. The PBS can be either in the form of a cube or a plane.

[0018] Figure 1A, and Figure IB, show two examples of using PBS with microLED ( ML)microdisplay and light-modulating microdisplay. In one case, the reflected image from the PBS is projected into the light-modulating (LM) microdisplay. The LM microdisplay changes the polarization, and the image can pass through the PBS. In another related case, the transmitted image from the PBS is projected into the LM microdisplay. The reflected image from the LM microdisplay is the output image.

[0019] Figure 1C shows a related embodiment where the images pass through a transparent structure where the LM 104 is put on the surface at an angle. The LM microdisplay 104 reflects the image from the ML 102 microdisplay.

[0020] Other optical elements can be used between the ML microdisplay and PBS or LM microdisplay and PBS. These optical structures can be lenses, polarizers, or other structures.

[0021] In another related embodiment, the total reflection surface can project the image from the ML microdisplays into the LM microdisplay. Here, the angle of the ML and LM microdisplays can be adjusted to allow the image to be reflected or transmitted depending on the required function.

[0022] Figure 2 shows another related embodiment of an optical structure 200, allowing the image 208 from an ML microdisplay 204 to be projected onto an LM microdisplay 202. Here, waveguide structure 208 is used. The output image 210 is reflected out of the LM microdisplay 206. The LM microdisplay and M L microdisplay can be on the same side of waveguide 208 or on two different sides.

[0023] There can be other optical elements between the ML microdisplay and waveguide or between the LM and waveguide.

[0024] In another related embodiment, the ML microdisplay has a full color image and one frame. Here, the LM microdisplay only modulates the brightness to create a higher resolution image and the color is defined by the LM microdisplay.

[0025] The module for figures 1A-1C and figure 2 can also have two modes, the first mode low power, where the ML and LM microdisplay have one frame where ML controls the color and peak brightness. And LM controls only the brightness for high resolution pixels. In high image quality mode, the ML and LM have subframes and each subframe is associated with a unique color.

[0026] In another related embodiment, figures 1A-1C and figure 2, there is more than one subframe. During each subframe a full color image is created in the ML microdisplay and the LM microdisplay is programmed to enhance the image resolution. In one case, a first image is created using ML full color microdisplay and front LM monochrome LM microdisplay. The error between the created image and actual image is calculated and a second image is created using ML and LM microdisplays. The first and second images are shown during two different subframes. There can be a 3rd image to and a 3rd subframe to reduce the error between the created images and the actual image.

[0027] In another related embodiment, the first image is created to limit the sub-pixel brightness error for each pixel within a threshold boundary. The threshold boundary can have an upper limit and a lower limit. Where the upper threshold limits the sub-pixel having a higher brightness than actual sub-pixel value and the lower threshold limits the sub-pixel having a lower brightness than actual sub-pixel. The second image is also created based on the difference between the created image and the actual image to reduce the error furthermore. This process can extend to more than the first and second image.

[0028] In one related embodiment, the subframes and images created for each subframe can be transitional between two actual images. Here, the 2nd or 3rd subframe can have information from the first actual image and 2nd actual image. The information can be interpolated data between the two actual images.

[0029] The functions performed in the processes and methods may be implemented in differing orders. Furthermore, the outlined steps and operations are only provided as examples, and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations without detracting from the essence of the disclosed embodiments.

[0030] The present invention relates to the optical system as an emissive display (e.g. microLED) where each pixel generates light as current passes through the emissive elements in the pixel. The emissive elements can be microLED. The invention also related to a method to use pixels with microLEDs to provide more control over the grayscale.

[0031] The optical system is an emissive display (e.g. microLED) where each pixel generates light as current passes through the emissive elements in the pixel. The emissive elements can be microLEDs.

[0032] The system can generate high-resolution images with lower brightness for display operation mode in one related embodiment. As for the display, the grayscale is an essential factor; the pixel and driving system is run in a mode that can provide more control over the grayscale.

[0033] During lighting mode, the image can be a lower resolution (combining a few pixels to form one larger pixel)— -also, the driving system and pixel drive are in higher current mode with lower grayscale capability. Here, the driving system can have two different subsystems: lighting and displays. The two subsystems can share some components.

[0034] The pixel is also designed to support the two functions. The pixel may have different bias conditions or two configurations for each driving mode in one case.

[0035] Figure 3 shows the optical system supporting the embodiments described here with a display 302 and a driving system 308. The display includes pixel 304, which can turn into a cluster of pixel 306 for lighting applications. The display 302 is connected to the driving system 308 through a connection 310.

[0036] Different drivers may be used for each operation mode if the display pixels are passive and an external driver provides the driving current. In another related embodiment, clustering the pixels increases the brightness for lighting mode by increasing the ON time.

[0037] While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

Claims1. A method to project an image from a microLED microdisplay(ML) into a light-modulating microdisplay(LM), the method comprising: having an ML microdisplay; having a LM microdisplay; and using a polarizing beamsplitter (PBS) to project the image from the ML microdisplay into the LM microdisplay to improve a resolution output.

2. The method of claim 1 , wherein the PBS is either in a form of a cube or a plane.

3. The method of claim 1, wherein other optical elements such as lenses and polarizers are used between the ML microdisplay and the PBS or the LM microdisplay and PBS.

4. The method of claim 1, a reflected image from the PBS is projected into the lightmodulating (LM) microdisplay.

5. The method of claim 4, wherein LM microdisplay changes a polarization, and the image passes through the PBS.

6. The method of claim 1 , wherein a transmitted image from the PBS is projected into the LM microdisplay and the reflected image from the LM microdisplay is an output image.

7. The method of claim 1 , wherein the images pass through a transparent structure where the LM is put on a surface at an angle.

8. The method of claim 7, wherein the LM microdisplay reflects the image from the ML microdisplay.

9. The method of claim 1 , wherein a total reflection surface projects the image from the ML microdisplays into the LM microdisplay.

10. The method of claim 9, wherein an angle of the ML and LM microdisplays is adjustable to allow the image to be reflected or transmitted depending on a required function.

11. A method to project an image from a microLED microdisplay(ML) into a light-modulating microdisplay (LM), the method comprising: having an ML microdisplay; having a LM microdisplay; and using a waveguide to project the image from the ML microdisplay into the LM microdisplay.

12. The method of claim 11, wherein an output image is reflected out of the LM microdisplay.

13. The method of claim 11 , wherein LM microdisplay and ML microdisplay are on the same side of waveguide or on two different sides.

14. The method of claim 11, wherein, the ML microdisplay has a full color image and one frame.

15. The method of claim 14, wherein the LM microdisplay only modulates the brightness to create a higher resolution image and the color is defined by the LM microdisplay.

16. A method to run an optical system, the method comprising: having a display and a driving system; having pixels with MicroLEDs; having the pixels in the display; using drivers for each operation mode if the display pixels are passive; and having an external driver providing a driving current.

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