Pixel shifting method in a projection system

Abstract

A projection method for pixel shifting includes a light source configured to emit light and a spatial light modulator configured to receive the light and generate modulated light. The spatial light modulator includes a plurality of micromirrors. The projection system includes a wobulation device configured to shift the modulated light by a fractional pixel. The projection system includes a controller configured to control the light source to emit light onto the spatial light modulator for each of a plurality of subperiods, and to shift the modulated light by a fractional pixel distance greater than a half-pixel distance between each of the plurality of subperiods using the wobulation device.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Patent Application No. 63 / 404,371, filed September 7, 2022, and European Patent Application No. 22217440.1, filed December 31, 2022, each of which is incorporated by reference herein in its entirety. [Background technology]

[0002] 1. Fields of Disclosure The present application relates generally to projection systems and methods.

[0003] 2. Background technology Digital projection systems typically utilize a light source and an optical system to project an image onto a surface or screen. The optical system can include components such as mirrors, lenses, waveguides, optical fibers, beam splitters, diffusers, and spatial light modulators (SLMs). The contrast of a projector indicates the projector's brightest output relative to its dimmest output. Contrast ratio is a quantifiable measure of contrast defined as the ratio between the luminance of the projector's brightest output and the luminance of the projector's dimmest output. This definition of contrast ratio is also referred to as the "native" contrast ratio.

[0004] Some projection systems are based on SLMs that perform spatial amplitude modulation, such as digital micromirror device (DMD) chips. A DMD may utilize a two-dimensional array of mirrors that can be controlled to generate an image. When it is desired to project an image with a higher resolution than the resolution of the DMD (e.g., an image with a greater number of pixels than the number of mirrors in the DMD), pixel shifting techniques may be used. In one comparison to pixel shifting techniques, sometimes referred to as "wobulation," the system may be controlled to effectively shift the modulator, or a device optically located after the modulator, by fractional pixels in a set pattern to create the appearance of displaying additional pixels. Summary of the Invention

[0005] Wobulation devices are used to implement pixel shifting techniques. A wobulation device, or wobulator, is a device that rapidly moves pixels between a set of fixed positions to create a high-resolution image. For example, a wobulator can move pixels in a square pattern to quadruple the display resolution, creating a 2x2 set of pixels for each physical DMD pixel.

[0006] The wobulator's transitions between positions can blur the display pixels, potentially reducing resolution and creating artifacts in the image projected by the DMD. Specifically, the observed "effective" point spread function (PSF) is the integral of light at all times for a given pixel. Thus, at least three artifacts from wobulation movement can affect the image projected by the DMD: increased pixel size, distorted pixel shape, and a shift in the pixel center of mass. The longer the time spent transitioning between positions, the larger the "effective" pixel (e.g., the projected pixel, the pixel seen by an observer of the projected image) provided by the wobulator. Furthermore, the more time and distance spent away from the "ideal" pixel position, the more deformation from the "ideal" pixel shape (e.g., the pixel shape without motion) occurs.

[0007] Furthermore, the position of the center of mass of each projected pixel is affected by the motion path of the wobulator. This movement of the center of mass of each pixel not only affects the resolution of the projected image, but also results in a dependency between the position of the image pixel pattern relative to the group of wobulator pixels. For example, a 1-pixel checkerboard pattern (e.g., a repeating 2x2 pixel pattern) may have different projected resolutions depending on how the checkerboard pattern is aligned with the group of wobulator sub-pixels.

[0008] The embodiments described herein provide mitigation techniques for reducing such artifacts. One mitigation technique involves controlling the DMD to an "off" position, essentially ceasing the projection of light onto the wobbulator while the wobbulator moves from one position to another. Another mitigation technique involves extending the path of movement of the wobbulator so that it moves between positions a distance greater than half the length of a pixel when increasing resolution in a particular direction. Such mitigation techniques reduce artifacts seen in images output from the wobbulator.

[0009] In an exemplary aspect of the present invention, a projection system with pixel shifting is provided, the projection system comprising: a light source configured to emit light; and a spatial light modulator configured to receive the light and generate modulated light. The spatial light modulator includes a plurality of micromirrors. The projection system comprises a wobulation device configured to shift the modulated light by a fractional pixel. The projection system comprises a controller configured to control the light source to emit light onto the spatial light modulator for each of a plurality of sub-periods, and to shift the modulated light by a fractional pixel distance that is greater than a half-pixel distance between each of the plurality of sub-periods using the wobulation device.

[0010] In an exemplary aspect of the present invention, there is provided a method for calibrating pixel shift in a projection system, the method including the steps of emitting light using a light source, receiving the light using a spatial light modulator, and modulating the light using the spatial light modulator to generate a modulated image, the modulated image including a plurality of pixels, the method including the steps of shifting the modulated light for each pixel of the modulated image by a fractional pixel distance during each of a plurality of sub-periods to generate a wobulated image, determining an amount of wobulation artifacts in the wobulated image, and adjusting the fractional pixel distance based on the determined amount of wobulation artifacts.

[0011] In another exemplary aspect of the present invention, a projection method for pixel shifting is provided, the projection method including: controlling a light source to emit light onto a plurality of micromirrors on a spatial light modulator for each of a plurality of subperiods; receiving the light using the plurality of micromirrors to generate modulated light for each of the plurality of subperiods; and shifting the modulated light by a fractional pixel distance greater than a half pixel distance between each of the plurality of subperiods.

[0012] Thus, various aspects of the present disclosure provide for the display of images with high dynamic range, high contrast ratio, and high resolution, leading to improvements in at least the fields of image projection, holography, signal processing, and the like. [Brief explanation of the drawings]

[0013] These and other more detailed and specific features of the various embodiments are more fully disclosed in the following description, which refers to the accompanying drawings.

[0014] [Figure 1A] 1A-1B are diagrams illustrating an exemplary spatial light modulator according to various aspects of the present disclosure. [Figure 1B] 1A-1B are diagrams illustrating an exemplary spatial light modulator according to various aspects of the present disclosure.

[0015] [Figure 2] FIG. 2 is a diagram illustrating an exemplary pixel shifting operation according to various aspects of the present disclosure.

[0016] [Figure 3] FIG. 3 is a diagram illustrating an exemplary wobulation path of a wobulation device according to various aspects of the present disclosure.

[0017] [Figure 4] FIG. 4 illustrates an exemplary checkerboard pattern according to various embodiments of the present disclosure.

[0018] [Figure 5A] 5A-5B are diagrams illustrating exemplary wobulation responses to the checkerboard pattern of FIG. 4 with small dots of light, according to various embodiments of the present disclosure. [Figure 5B] 5A-5B are diagrams illustrating exemplary wobulation responses to the checkerboard pattern of FIG. 4 with small dots of light, according to various embodiments of the present disclosure.

[0019] [Figure 6] FIG. 6 illustrates another exemplary checkerboard pattern according to various embodiments of the present disclosure.

[0020] [Figure 7] FIG. 7 illustrates an exemplary wobulation response to the checkerboard pattern of FIG. 6 with dots of light, according to various embodiments of the present disclosure.

[0021] [Figure 8] FIG. 8 is a diagram illustrating an example wobulation response to the checkerboard pattern of FIG. 6 with real pixel point spread functions, according to various aspects of the present disclosure.

[0022] [Figure 9] FIG. 9 illustrates a wobulation response to an example pattern where the wobulator has an instantaneous transition time, in accordance with various aspects of the disclosure.

[0023] [Figure 10] 10A-B illustrate wobulation responses to the example patterns of FIG. 9 when the wobulators have non-zero transition times, in accordance with various aspects of the present disclosure.

[0024] [Figure 11] FIG. 11 is a diagram illustrating the wobulation response to an exemplary pattern of single pixel high horizontal lines when the wobulator has an instantaneous transition time, in accordance with various aspects of the present disclosure.

[0025] [Figure 12] FIG. 12 is a diagram illustrating the wobulation response to an exemplary pattern of single pixel high horizontal lines when the wobulator has a non-zero transition time, in accordance with various aspects of the present disclosure.

[0026] [Figure 13]13 and 14 are diagrams illustrating wobulation responses to example patterns where the wobulator has an instantaneous transition time, in accordance with various aspects of the present disclosure. [Figure 14] 13 and 14 are diagrams illustrating wobulation responses to example patterns where the wobulator has an instantaneous transition time, in accordance with various aspects of the present disclosure.

[0027] [Figure 15] 15 and 16 are diagrams illustrating wobulation responses to example patterns when the wobulator has a non-zero transition time, in accordance with various aspects of the present disclosure. [Figure 16] 15 and 16 are diagrams illustrating wobulation responses to example patterns when the wobulator has a non-zero transition time, in accordance with various aspects of the present disclosure.

[0028] [Figure 17] FIG. 17 shows the superposition of the wobulation responses of FIGS.

[0029] [Figure 18] FIG. 17 shows the superposition of the wobulation responses of FIGS. 15 and 16.

[0030] [Figure 19] FIG. 19 illustrates an exemplary wobulation path implementing a blanking mitigation method in accordance with various aspects of the present disclosure.

[0031] [Figure 20A] FIG. 20A is a diagram illustrating an exemplary wobulation path along the x-axis, according to various aspects of the present disclosure.

[0032] [Figure 20B] FIG. 20B is a diagram illustrating an exemplary wobulation path along the y-axis, according to various aspects of the present disclosure.

[0033] [Figure 21] FIG. 21 illustrates a wobulation response to an exemplary checkerboard pattern when a wobulator is performing a blanking mitigation method, according to various aspects of the present disclosure.

[0034] [Figure 22] FIG. 22 illustrates a wobulation response to an exemplary checkerboard pattern when the wobulator is not implementing a mitigation method, in accordance with various aspects of the present disclosure.

[0035] [Figure 23] FIG. 23 illustrates an example process flow for an example pixel shifting method including blanking, in accordance with various aspects of the present disclosure.

[0036] [Figure 24] FIG. 24 is a diagram illustrating an exemplary extended wobulation path, according to various aspects of the present disclosure.

[0037] [Figure 25] FIG. 25 illustrates a wobulation response to an exemplary checkerboard pattern when the wobulator is configured with a non-extending wobulation path, in accordance with various aspects of the disclosure.

[0038] [Figure 26] FIG. 26 illustrates a wobulation response to an exemplary checkerboard pattern when the wobulator is configured with an extended wobulation path, in accordance with various aspects of the disclosure.

[0039] [Figure 27] FIG. 27 illustrates an exemplary process flow for calibrating a wobulation path, according to various aspects of the present disclosure.

[0040] [Figure 28]FIG. 28 illustrates a block diagram of an exemplary projector display system according to various aspects of the disclosure.

[0041] [Figure 29] FIG. 29 is a diagram illustrating an optical configuration of an exemplary projector system according to various aspects of the present disclosure.

[0042] [Figure 30] FIG. 30 illustrates an exemplary projection lens according to various aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0043] The present disclosure and aspects thereof may be embodied in various forms, including computer-implemented methods, computer program products, computer systems and networks, user interfaces, and hardware, devices, or circuits controlled by application programming interfaces, as well as hardware-implemented methods, signal processing circuits, memory arrays, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc. The above summary is intended only to provide a general idea of ​​various aspects of the present disclosure and is not intended to limit the scope of the disclosure in any way.

[0044] In the following description, numerous details are set forth, such as the configuration, timing, and operation of optical devices, in order to provide an understanding of one or more aspects of the present disclosure. Those skilled in the art will readily appreciate that these specific details are merely examples and are not intended to limit the scope of the present application.

[0045] Additionally, while this disclosure primarily focuses on examples in which various circuits are used in digital projection systems, it will be understood that this is merely one example implementation. It will further be understood that the disclosed systems and methods may be used in any device that needs to project light, such as cinemas, consumer and other commercial projection systems, heads-up displays, virtual reality displays, etc.

[0046] Pixel Shift The optics of a projection system utilizing a spatial light modulator (SLM) can be broadly categorized into two parts: the optics located on the illumination side (i.e., optically upstream of the SLM) and the optics located on the projection side (i.e., optically downstream of the SLM). The SLM itself contains multiple modulation elements, arranged, for example, in a two-dimensional array. Each modulation element receives light from the illumination optics and transmits the light to the projection optics. In some examples, an SLM can be implemented as a digital micromirror device (DMD) chip, which is described in more detail below. However, typically, a DMD contains a two-dimensional array of reflective elements (micromirrors or simply "mirrors") that selectively reflect or reject light toward the projection optics based on the position of each reflective element.

[0047] 1A-1B show various views of an exemplary DMD 100 according to various aspects of the present disclosure. FIG. 1A is a plan view of the DMD 100, and FIG. 1B is a partial cross-sectional view of the DMD 100 taken along line IB shown in FIG. 1A. The DMD 100 includes a plurality of square micromirrors 102 arranged in a two-dimensional rectangular array on a substrate 104. In some embodiments, the DMD 100 may be a digital light processor (DLP) device. Each micromirror 102 may correspond to one pixel of the final projected image and may be configured to tilt, via electrostatic or other action, about a rotation axis 108 shown for one particular subset of the micromirrors 102. The individual micromirrors 102 have a width 112 and are arranged with a gap of width 110 between them. The micromirrors 102 may be formed of or coated with any highly reflective material, such as aluminum or silver, thereby enabling specular reflection of light. The gaps between the micromirrors 102 may be absorptive, such that input light entering the gaps is absorbed by the substrate 104.

[0048] Although FIG. 1A explicitly shows only a few representative micromirrors 102, in practice, the DMD 100 may include many more individual micromirrors. The resolution of the DMD 100 refers to the number of micromirrors in the horizontal and vertical directions. In some examples, the resolution may be 2K (2048×1080), 4K (4096×2160), 1080p (1920×1080), consumer 4K (3840×2160), etc. Furthermore, in some examples, the micromirrors 102 may be rectangular and arranged in a rectangular array, hexagonal and arranged in a hexagonal array, and so forth. Furthermore, while FIG. 1A shows the rotation axis 108 extending diagonally, in some implementations, the rotation axis 108 may extend vertically or horizontally.

[0049] As shown in FIG. 1B , each micromirror 102 may be connected to a substrate 104 by a yoke 114 rotatably connected to the micromirror 102. The substrate 104 includes a plurality of electrodes 116. Although only two electrodes 116 per micromirror 102 are visible in the cross-sectional view of FIG. 1B , each micromirror 102 may actually include additional electrodes. Although not specifically shown in FIG. 1B , the DMD 100 may further include a spacer layer, a support layer, hinge components for controlling the height or orientation of the micromirrors 102, etc. The substrate 104 may include electronic circuitry associated with the DMD 100, such as CMOS transistors, memory elements, etc.

[0050] Depending on the specific operation and control of the electrodes 116, individual micromirrors 102 can be switched between an “on” position, an “off” position, and a non-actuated or neutral position. When a micromirror 102 is in the on position, the micromirror is actuated to an angle of, for example, −12° (i.e., rotated 12° counterclockwise relative to the neutral position) to specularly reflect input light 106 as on-state light 118. When a micromirror 102 is in the off position, the micromirror is actuated to an angle of, for example, +12° (i.e., rotated 12° clockwise relative to the neutral position) to specularly reflect input light 106 as off-state light 120. The off-state light 120 can be directed toward a light dump that absorbs the off-state light 120. In some examples, the micromirror 102 can be non-actuated and positioned parallel to the substrate 104. The specific angles shown in FIGS. 1A-1B and described herein are merely exemplary and not limiting. In some embodiments, the on position angle and the off position angle may each be between ±12 degrees and ±13 degrees inclusive.

[0051] In some implementations, the resolution of the DMD 100 may be lower than the desired resolution of the projected image. For example, it may be desired to project an image having 4K resolution, but DMDs with 4K resolution may have limited or no commercial availability, be cost-prohibitive, etc. In such implementations, it may be possible to control a relatively low-resolution DMD 100 to effectively display additional pixels in the projected image. For example, a 2K mirror array may be controlled to display a 4K projected image, or a 1080p mirror array may be controlled to display a consumer 4K projected image. Pixel shifting techniques may be used to affect this control.

[0052] One exemplary pixel shifting technique (wobulation) uses some method (e.g., optical methods) to effectively shift DMD 100 by fractional pixels in a set pattern to display additional pixels. An example of such a pixel shifting technique is shown in FIG. 2. In the pixel shifting technique of FIG. 2, a frame display period T (typically divided by a quarter at the projector frame rate) is divided into four subperiods, each with a duration of T / 4. At time t0, which corresponds to the beginning of the first subperiod and thus the beginning of frame display period T, an image is projected onto the screen. Although only a 2×2 subset of pixels in first resultant image 201 is shown in FIG. 2, first resultant image 201 actually has a resolution corresponding to the relatively low resolution of DMD 100. At time t1, which corresponds to the beginning of the second subperiod, the image is shifted half a pixel to the right, thereby producing second resultant image 202 on the screen. At time t2, which corresponds to the beginning of the third subperiod, the image is shifted half a pixel down, thereby producing third resultant image 203 on the screen. At time t3, corresponding to the start of the fourth sub-period, the image is shifted half a pixel to the left, thereby generating a fourth resultant image 204 on the screen. At the end of the frame display period T, the image is shifted half a pixel up, so that it may correspond to its original position for starting the display of the next frame. As can be seen from FIG. 2, each shift increases the effective display resolution (e.g., the resolution observed by a viewer of the image). The direction of the shift is not limited to the column and row directions of the pixel array (i.e., up, down, left, right), but may also be diagonal (e.g., diagonal). Furthermore, although FIG. 2 illustrates a pixel shifting technique that shifts the image in two dimensions, in certain embodiments, the pixel shifting may occur only in one dimension, in a back-and-forth manner.

[0053] In some examples, the wobulation device performs a pixel shift on the output of DMD 100, allowing the superimposed output of DMD 100 to be viewed as an output of higher resolution. The wobulation device is located optically after DMD 100 so that the output of DMD 100 is received as the input of the wobulation device. The wobulation device may shift in a single direction (e.g., doubling only the vertical resolution or doubling only the horizontal resolution) or may shift along multiple axes, such as a 2x2 positioning, which doubles the resolution along both axes and effectively quadruples the number of output pixels.

[0054] FIG. 3 provides a graph illustrating the operation of a wobulation device between four positions, according to one embodiment. In FIG. 3, the wobulator shifts between a first position 300, a second position 305, a third position 310, and a fourth position 315. For example, at time t0, which corresponds to the start of the first subperiod and thus the start of the frame display period T, the wobulation device is located at the first position 300. At time t1, which corresponds to the start of the second subperiod, the wobulator shifts right from the first position 300 to the second position 305. At time t2, which corresponds to the start of the third subperiod, the wobulator shifts downward from the second position 305 to the third position 310. At time t3, which corresponds to the start of the fourth subperiod, the wobulator shifts left from the third position 310 to the fourth position 315. At the end of the frame display period T, the wobulator shifts upward from the fourth position 315 to the first position 300. Each "point" in the graph represents the position of the wobulator over the display period T. As can be seen in Figure 3, as the wobulator transitions between positions, a small amount of light may be "spread" over the path of travel, as will be explained in more detail below.

[0055] 4 provides an example wobulated output in response to an example checkerboard pattern 400. Checkerboard pattern 400 includes four "checks," each of which is a basic 2x2 checkerboard pattern. Each "check" in the checkerboard pattern consists of an "on" pixel in the upper left and lower right corners and an "off" pixel in the upper right and lower left corners. This pattern results in two pixels (along the diagonal) being active within each "check."

[0056] 5A-5B provide an example wobulation response to an input checkerboard pattern 300. In the example wobulation responses of FIGS. 5A-5B, as well as other example responses provided herein, point source pixels are analyzed rather than pixels with a typical point spread function (PSF) reflected from each micromirror 202 in DMD 100. A typical pixel PSF covers an area at least as large as the pixel itself (e.g., as large as each micromirror 202). FIGS. 5A-5B provide eight pixels for each wobulated output pixel.

[0057] In Figure 5A, the wobulation remains near the corners of each square for a relatively large amount of the full subpixel cycle. The illustrated pixel brightness is related to the transition time between each position (e.g., between each corner). In Figure 5B, for comparison, the wobulation path is the same, but more time is spent transitioning compared to Figure 5A. Thus, in Figure 5B, more light is seen along the paths outside the corner positions, and the corners are less bright than those seen in Figure 5A.

[0058] Pixel shift artifacts To demonstrate exemplary artifacts on effective (or projected) pixels, a scaled test pattern of two separated checkerboards, shown in FIG. 6, is used. In FIG. 6, the leftmost checkerboard 600 is aligned with and completely contained within a 2×2 wobulator subpixel grid. Specifically, each of the four pixels in the leftmost checkerboard 600 is created by the same wobulator shifting between four different positions. However, the rightmost checkerboard 605 spans two separate 2×2 subpixel grids. The two left pixels in the rightmost checkerboard 605 are created by wobbling (e.g., shifting with a wobulator) a first pixel, and the two right pixels in the rightmost checkerboard 605 are created by wobbling a second pixel.

[0059] FIG. 7 shows exemplary wobulation responses for the leftmost checkerboard 600 and the rightmost checkerboard 605 of FIG. 6 , using artificially small pixels for ease of visualization. Specifically, the leftmost wobulation response 700 corresponds to the leftmost checkerboard 600, and the rightmost wobulation response 705 corresponds to the rightmost checkerboard 605. The effective pixels seen in each wobulation response are the integral of light over the entire path of the wobulation device. As can be seen in FIG. 7 , the transition time affects the leftmost wobulation response 700 and the rightmost wobulation response 705 differently. In the case of the leftmost wobulation response 700, because the checkerboard pattern is within a single 2×2 wobulation grid, the effect on the effective pattern is to move each of the pixels closer together and toward the center of the 2×2 wobulator grid. In the case of the rightmost wobulation response 705, the checkerboard pattern lies across two separate wobulator grids, so the effective pattern moves each of the pixels away from each other on the x-axis (while still moving towards the center of the 2x2 wobulator grid).

[0060] Figure 8 shows the same wobulation response with a pixel PSF of actual size. In Figure 8, the light has different shapes in response to two identical checkerboard input patterns. Specifically, the checks on the right are further apart, with lower valleys between pixels, compared to the checks on the left. Thus, the wobulation artifacts depend on both the phasing of the input pattern and the wobulation grid itself.

[0061] Artifacts present in the wobulation output are even more visible within repeating patterns. FIG. 9, for example, shows the wobulation response to an exemplary pattern when the wobulator has ideal wobulation motion. A wobulator characterized by ideal wobulation motion, as referred to herein, can be a wobulator with instantaneous transition times. For comparison, FIG. 10 shows the wobulation response to the exemplary pattern of FIG. 9 when the wobulator has non-ideal wobulation motion or non-zero transition times. In FIG. 10, the left and right sides of the pattern show different artifact orientations due to the phasing of the checkerboard relative to the 2×2 wobulator pixel cluster. In FIG. 9, the checkerboard pattern is clearly visible. However, in FIG. 10, there is a clear pattern of artifacts due to non-ideal wobulator motion affecting the size, shape, and position of the effective output pixels.

[0062] Another example pattern affected by non-ideal wobulator motion is a pattern of horizontal lines that are a single pixel high. Figure 11 shows the ideal wobulator response to a horizontal line. For comparison, Figure 12 shows the non-ideal wobulator response to a horizontal line. As can be seen in Figure 12, the wobulator motion results in horizontal modulation of the line compared to the ideal output of a straight line.

[0063] The modulation in Figure 12 can be further investigated by looking at small spots of light rather than the full PSF pixels of Figures 11 and 12. Figure 13 shows a single pixel-high horizontal line with a small spot of light for an ideal wobulator (i.e., a wobulator with no transition time). Figure 14 shows a wobulated output with a realistic PSF corresponding to the horizontal line in Figure 13.

[0064] However, when a realistic wobulator with a non-zero transition time between positions is used, modulation appears in the output. Figure 15 shows a single-pixel-high horizontal line with a small light spot for a realistic wobulator with a non-zero transition time. Figure 16 shows the wobulated output with a realistic PSF corresponding to the horizontal line in Figure 15.

[0065] Superposition of wobulation responses further illustrates the artifacts produced by wobulator movement. For example, Figure 17 shows a superposition of the wobulation responses of Figures 13 and 14 when the wobulator has an instantaneous transition time. For comparison, Figure 18 shows a superposition of the wobulation responses of Figures 15 and 16 when the wobulator has a non-instantaneous transition time. The superposition in Figure 18 illustrates the line "bumps" produced by realistic wobulator movement.

[0066] Mitigation method To mitigate artifacts generated by wobulator movement between positions, one mitigation method proposed herein involves “blanking” (e.g., turning off) the light projected by DMD 100 during the transition time of the modulator device. FIG. 19 provides a graph illustrating the operation of the wobulation device between four positions while performing “blanking,” according to one embodiment. Specifically, the wobulation device shifts between a first position 1900, a second position 1905, a third position 1910, and a fourth position 1915. When transitioning between each position, DMD 100 controls multiple micromirrors 102 to the “off” position for at least a portion of the transition time between positions, thereby directing light away from the wobulation device and toward a light dump. Thus, light that would previously be visible during the transition between each position (as shown in FIG. 3 ) is eliminated.

[0067] Figures 20A and 20B illustrate an exemplary operation of a wobulation device. Figure 20A shows movement of the modulator along the x-axis, and Figure 20B shows movement of the modulator along the y-axis. Periods during which "blanking" of light occurs are indicated by "B" and occur during the transition periods between each position.

[0068] An example of a checkerboard pattern for a wobulation device that implements "blanking" is shown in Figure 21. For comparison, an example of a checkerboard pattern for a wobulation device that does not implement "blanking" is shown in Figure 22. The example of Figure 21 has fewer artifacts. While "blanking" provides artifact elimination, "blanking" also results in loss of light to the light dump.

[0069] Figure 23 provides a particular example method 2300 for performing a "blanking" mitigation technique. Method 2300 of Figure 23 may be performed by a controller or control circuitry associated with controlling DMD 100 and the wobulation device, such as controller 2816 described with respect to Figure 28, and may be implemented using hardware, software, firmware, or a combination thereof. In some examples, method 2300 is implemented as instructions stored on a non-transitory computer-readable medium, such as a hard disk or other storage medium included in or associated with the projection system.

[0070] In method 2300, a series of images is displayed using image data comprising a series of frames. The image data is divided into a number of frame periods, each corresponding to a frame duration T; for example, a 60 Hz display has a frame period T of 1 / 60 seconds. In operation 2301, the frame period is divided into N subperiods, where N is an integer greater than 1. Preferably, N is 4 to implement a pixel shift pattern similar to that illustrated in FIG. 2 and a wobulation device movement pattern similar to that illustrated in FIG. 3, but in other implementations, N may be 6 or another number other than 4. In operation 2302, a counter I is initialized to 1. Then, in operation 2303, for the Ith subperiod, an image is projected by the DMD 100 through the wobulation device. Operation 2303 can include suboperations such as causing a light source of the projection system to emit light and controlling a spatial light modulator (e.g., the DMD 100 of FIG. 1) to modulate the light to form an image. The image is maintained for a duration of T / N. In the example of a 60Hz display using four sub-periods per frame, the duration of this sub-period is (1 / 240) seconds.

[0071] At the end of the subperiod in operation 2304, counter I is compared to N to determine if the subperiod is the last subperiod of the frame. If counter I is not equal to N, counter I is incremented by 1 in operation 2305. In operation 2306, the micromirrors 102 of the DMD 100 are switched to the "off" position to provide "blanking" of the wobulation device. In operation 2307, the wobulation device is shifted so that the pixels are shifted. As shown in FIG. 19, in an example where four subperiods are provided per frame and the pixel shift follows a square pattern as in FIG. 2, this corresponds to a half-pixel shift. Alternatively, four subperiods are provided per frame and the pixel shift follows a diamond or rectangular pattern; six subperiods are provided per frame and the pixel shift follows a rectangular or hexagonal pattern; three subperiods are provided per frame and the pixel shift follows a triangular pattern; two subperiods are provided per frame and the pixel shift follows a linear (back and forth) pattern, and so on. In some implementations, the number of subperiods can be on the order of tens (or more), and the pixel shift can approximate a circular pattern or a complex shape. As the wobulation device approaches a new position, micromirrors 102 of DMD 100 are switched to the "on" position in operation 2308. The duration of the wobulation device blanking (e.g., the duration of operations 2306-2308) can be, for example, 5% of the subperiod duration, 10% of the subperiod duration, 25% of the subperiod duration, etc.

[0072] Operation 2303 is then repeated for the next subperiod until counter I is equal to N. At this point, in operation 2309, the frame is incremented and method 2300 returns to operation 2302. Operations 2302-2309 are repeated for the duration of the image display and may continue until the end of the media content is reached, an operation issues a pause or stop command, etc.

[0073] Another artifact mitigation method disclosed herein provides an extended wobulation path for the movement of the wobulation device. Conventionally, each wobulator position corresponds to a quadrant or corner of the micromirror 102, and the wobulation device represents each micromirror 102 as four "pixels" (e.g., effective pixels). Thus, each "effective" pixel is evenly spaced along the micromirror 102, and the wobulation device shift is a half-pixel (0.5) distance.

[0074] However, by shifting the wobulation device beyond half a pixel distance, the wobulation device compensates for the shift in pixel position caused by non-instantaneous transition times (see the discussion of Figures 7 and 8 for how some wobulation artifacts result from the effective center of a subpixel moving closer to or farther from the center of the four subpixels), eliminating some of the artifacts without losing light. Figure 24 shows an exemplary extended wobulation path compared to a "traditional" wobulation path. In the example of Figure 24, the extended wobulation path is 0.55 pixel distance (or 1.1 times the distance of the "traditional" wobulation path). However, the extended wobulation path can be any value greater than half a pixel distance (e.g., greater than 50% of the pixel distance) that eliminates artifacts from the wobulation output image. In some embodiments, the extended wobulation path is between 50.1% of the pixel distance and 60% of the pixel distance. In other embodiments, the extended wobulation path is greater than 60% of the pixel distance, such as values ​​in the range of 60% to 70%, values ​​in the range of 70% to 80%, values ​​in the range of 80% to 90%, and values ​​in the range of 90% to 100%.

[0075] An example of a checkerboard pattern for a wobulation device implementing a "traditional" wobulation path is provided in Figure 25. For comparison, an example of a checkerboard pattern for a wobulation device implementing an extended wobulation path is shown in Figure 26. The example in Figure 26 has fewer artifacts.

[0076] 27 provides a particular exemplary method 2700 for calibrating the wobulation path of a wobulation device. Method 2700 may be performed during the initial setup of the projection system implementing DMD 100 and the respective wobulation device.

[0077] In operation 2701, the DMD 100 is controlled to project a modulation image. For example, the DMD 100 may be controlled to project a test image, such as the checkerboard image of FIG. 9 or the horizon image of FIG. 11. The modulation image may be projected onto a screen so that an operator performing the calibration can view the modulation image. In some embodiments, the DMD 100 first projects an image having a "normal" pixel size PSF. In operation 2702, the pixel size included in the modulation image is adjusted. In some implementations, an aperture is added to the projection system to reduce the pixel size during calibration, making artifacts more easily visible during calibration.

[0078] In operation 2703, the amount of wobulation artifacts in the wobulation image is determined. In operation 2704, the size of the wobulation path is adjusted based on the amount of wobulation artifacts. For example, the size of the wobulation path is adjusted until the artifacts in the modulation image are reduced to a desired level. For example, a dial, touch screen, or other type of user interface is turned or otherwise interacted with to adjust the size of the wobulation path (e.g., to increase the size of the wobulation path to greater than half a pixel distance). The operator adjusts the size of the wobulation path until the artifacts in the modulation image are reduced as desired.

[0079] In some examples, the artifacts depend on the frame rate of the display. Thus, method 2700 may be performed for a frame rate corresponding to the frame rate of the respective display, with the frame rate held constant for the duration of calibration method 2700. In some examples, a greater extension of the wobulation path may be required to adequately mitigate wobulation artifacts when operating at higher frame rates (e.g., 120 Hz) than at lower frame rates (e.g., a wobulation path of 0.60 pixel size may be useful at 120 Hz to mitigate artifacts, while a wobulation path of 0.50 pixel size may be sufficient to avoid wobulation artifacts at 60 Hz).

[0080] Additionally, although method 2700 is described with respect to an operator calibrating a wobulation path, in some examples, a controller or control circuitry associated with controlling DMD 100 and the wobulation device, such as controller 2816 described with respect to FIG. 28, can implement method 2700 using hardware, software, firmware, or a combination thereof. In some examples, method 2700 is implemented as instructions stored on a non-transitory computer-readable medium, such as a hard disk or other storage medium included in or associated with the projection system. For example, controller 2816 can store a model that describes a desired output modulation image or ideal wobulation path for a given frame rate. Controller 2816 then selects a wobulation path based on the model.

[0081] Although the "blanking" mitigation described in method 2300 and the extended wobulation path mitigation described in method 2700 are described separately, in some instances these mitigation methods are complementary and may be performed simultaneously. The amount of each technique applied can be adjusted to balance light loss and artifact mitigation effectiveness based on the wobulation device used.

[0082] While the embodiments described herein are primarily concerned with doubling the resolution, in some instances, wobulation techniques may be used to increase the resolution of, for example, DMD 100 by more than two times, such as three or four times. In embodiments where the resolution is tripled, the image is shifted by approximately one-third (⅓) pixel distance rather than half a pixel distance. Thus, in the enhanced wobulation path mitigation method, the wobulation path is adjusted to be greater than one-third pixel distance. In embodiments where the resolution is quadrupled, the image is shifted by approximately one-quarter (¼) pixel distance. Thus, in the enhanced wobulation path mitigation method, the wobulation path is adjusted to be greater than one-quarter pixel distance.

[0083] projection device FIG. 28 illustrates one possible embodiment of a suitable image projector display system implementing the described mitigation techniques. In the illustrated embodiment, the projection display system is configured as a dual / multi-modulator projection system 2800. The projection system 2800 uses a light source 2802 to provide the desired illumination to the projector system so that the final projected image is sufficiently bright for the intended viewer of the projected image. The light source 2802 may comprise any suitable light source, such as, but not limited to, a xenon lamp, one or more lasers, a coherent light source, and a partially coherent light source. Additionally, the optical systems described herein may implement optical fibers to transmit light from the light source 2802 to optical elements in the optical system. While the light source and the optical fiber may be referred to separately, it should be understood that the optical fiber is a component of the light source. Thus, a reference to only the light source does not exclude the optical fiber.

[0084] In some embodiments, the optical fiber is a rectangular optical fiber or a rectangular array of optical fibers with an aspect ratio that matches a downstream modulator, such as first modulator 2806 and / or second modulator 2810 .

[0085] Light 2804 from light source 2802 illuminates first modulator 2806, which, via a set of optional optics 2808, illuminates second modulator 2810. Light from second modulator 2810 can be projected by projection lens 2812 (or other suitable optics) to form a final projected image on screen 2814. In some examples, a wobulation device is implemented within projection lens 2812. In other examples, a wobulation device can be optically located between second modulator 2810 and projection lens 2812.

[0086] The first modulator 2806 and the second modulator 2810 are controlled by a controller 2816, which receives input image and / or video data, performs a particular image processing algorithm, gamut mapping algorithm, or other such appropriate processing on the input image / video data, and outputs control / data signals to the first modulator 2806 and the second modulator 2810 to achieve a desired final projected image on the screen 2814. Additionally, in some projector systems, it may be possible to modulate the light source 2802 (control lines not shown) to achieve further control over the image quality of the final projected image, depending on the light source.

[0087] Light recycling module 2803 is shown in Figure 28 as a dotted box that may be placed in the light path from light source 2802 to first modulator 2806. It may be understood that light recycling may be inserted into the projector system at various points in the projector system. For example, light recycling may be placed between first modulator 2806 and second modulator 2810. Furthermore, light recycling may be placed at more than one point in the light path of the display system.

[0088] While the embodiment of FIG. 28 is presented in the context of a dual-multi-modulation projection system, it should be understood that the techniques and methods of the present invention apply to single-modulation or other dual-multi-modulation display systems. For example, a dual-modulation display system comprising a backlight, a first modulator (e.g., an LCD), and a second modulator (e.g., an LCD) can employ appropriate optical components and image processing methods and techniques to affect the performance and efficiency described herein in the context of a projection system. Also, while FIG. 28 illustrates a two-stage or dual-modulator display system, it should be understood that the methods and techniques of the present application can also be applied to display systems with only one modulator, or display systems with three or more modulators (multi-modulators). The scope of the present invention encompasses these various alternative embodiments.

[0089] 29 shows another exemplary projection system 2900. Projection system 2900 includes an illumination assembly 2904 (e.g., illumination optics) that receives light from a fiber input 2902 and provides the light to a modulation assembly 2906. Modulation assembly 2906 includes a prism 2908 and a modulator 2910 (e.g., a reflector device). Modulator 2910 may be configured as a digital light processing (DLP) device, a DMD, or the like.

[0090] In some examples, the light from fiber input 2902 is a white light input, and prism 2908 is a white light prism. In such cases, prism 2908 includes several prism pieces. For example, prism 2908 may be provided with a spectral filter, such as a yellow notch filter. Additional components may function as a TIR prism. In some embodiments, modulation assembly 2906 includes three modulators 2910 (e.g., three chips) for modulating the received white light. Prism 2908 splits the white light into several color beams (e.g., three color channels), one color beam for each modulator 2910. A controller (such as controller 2816) can be coupled to each modulator 2910 to control the modulation of each color beam. The modulators 2910 then modulate each color beam before combining the modulated color beams in prism 2908. In other embodiments, modulators 2910 directly modulate the white light. In both embodiments, modulation assembly 2906 then relays the output beam to projection optics 2914 of projection system 2900. In some embodiments, projection optics 2914 is included in the projection lens. In other embodiments, a portion or section of projection optics 2914 is included in the projection lens. In some examples, projection optics 2914 includes a wobulation device.

[0091] In another example, projection system 2900 includes several fiber inputs 2902 from several color channels, such as a red channel, a blue channel, and a green channel. In such a case, the illustrated illumination assembly 2904 receiving the fiber inputs 2902 corresponds to only a single color channel provided to prism 2908. Several illumination assemblies 2904 may be included to direct light from the fiber inputs to prism 2908. In this example, prism 2908 is a color light prism that receives each fiber input 2902 and redirects each color channel to a respective modulator 2910. Following modulation, the modulated color channels are combined and directed to projection optics 2914.

[0092] In some examples, the fiber input 2902 is a high etendue source. Etendue is a measure of the radiating area multiplied by the solid angle, mm 2 *sr (steradian), M 2 It is related to terms such as the coefficient or beam parameter product (BPP). More specifically, the etendue is π*area*NA 2 Thus, the light projected by a single fiber optic input has a lower etendue than the light projected by a cluster of fiber optic inputs (such as the multiple inner fibers 710 in FIG. 7). A high etendue light source may have a lower etendue than the light projected by a cluster of fiber optic inputs (such as the multiple inner fibers 710 in FIG. 7). 2 *sr~50mm 2 A single fiber disclosed herein having a diameter of about 450 microns may have an etendue of about 0.024 mm 2 *sr. A fiber with a diameter of about 100 microns would have an etendue of about 0.0012 mm 2 *It may have an etendue of sr.

[0093] In some examples, the illumination assembly 2904 achieves a high f / number with a narrow illumination angle while maintaining uniformity of the light illuminated onto the modulator 2910. The f / number (denoted as f / #) is the ratio of the focal length of the system to the diameter of the aperture. The f / # of the light illuminated onto the prism 2908 may be in the range of f / 10 to f / 20.

[0094] In some embodiments, the projection optics 2914 are provided within a projection lens architecture. FIG. 30 is an exploded view of an exemplary projection lens system 3000 according to various aspects of the present disclosure. The projection lens system 3000 has a modular design. The projection lens system 3000 includes a Fourier section 3001 (e.g., a Fourier lens assembly) configured to form a Fourier transform of an object at an exit pupil, an aperture 3002, and a zoom section 3003 (also referred to as a zoom lens assembly). The spatial Fourier transform imposed by the Fourier section 3001 converts the propagation angle of each diffraction order of the modulated light to a corresponding spatial position on the Fourier plane. The Fourier section 3001 thereby enables the selection of desired diffraction orders and the rejection of undesired diffraction orders by spatial filtering in the Fourier plane. The spatial Fourier transform of the modulated light in the Fourier plane is equivalent to the Fraunhofer diffraction pattern of the modulated light.

[0095] The Fourier unit 3001 includes a first mounting portion 3004, which may include threads, fasteners, or the like. The zoom unit 3003 includes a second mounting portion 3005, which may include complementary threads, fasteners, or the like to enable mating with the first mounting portion 3004. In one embodiment, the first mounting portion 3004 includes male threads and the second mounting portion 3005 includes female threads, or vice versa. In another embodiment, the first mounting portion 3004 and the second mounting portion 3005 are configured for a friction fit, in which case one or more fastening elements, such as screws, cams, flanges, or the like, may be provided. In yet another embodiment, the first mounting portion 3004 may include one or more radial pins and the second mounting portion 3005 may include a corresponding number of L-shaped slots, or vice versa, thereby connecting the Fourier unit 3001 and the zoom unit 3003 using a bayonet connection. In these examples, the Fourier section 3001 may be removably attached to the zoom section 3003 to provide a modular assembly.

[0096] 30 depicts the Fourier section 3001 and the zone section 3003 as being completely separable, the disclosure is not so limited. In some implementations, the Fourier section 3001 and the zoom section 3003 are only partially separable, for example, by providing an access in one of the Fourier section 3001 and the zoom section 3003. The access may be a slot, door, window, or the like, through which an operator can access the opening 3002 and / or replace the opening 210. In such implementations, the Fourier section 3001 and the zoom section 3003 may be bonded (e.g., via adhesive on the first mounting section 3004 and / or the second mounting section 3005) to prevent complete separation. Alternatively, the Fourier section 3001 and the zoom section 3003 may comprise a unitary housing including the mounting section.

[0097] The aperture 3002 is configured to block a portion (e.g., modulated light corresponding to one or more diffraction orders) of the light in the projection lens system 3000 (e.g., modulated light provided via the modulation assembly 2906). As shown in FIG. 30, the aperture 3002 is, for example, a square opening with sides measuring 6 mm. FIG. 30 also shows an optical axis 3010 of the projection lens system 3000. When assembled, the Fourier section 3001 and the zoom section 3003 are substantially coaxial with each other and with the optical axis 3010. In some embodiments (e.g., depending on the illumination angle), the aperture 3002 is also substantially coaxial with the optical axis 3010. However, in other implementations, the aperture 3002 may not be substantially coaxial with the optical axis 3010. In some examples, the aperture 3002 is selected to achieve a desired "small point of light" in operation 2702 of the calibration method 2700.

[0098] The projection lens system 3000 may include or be associated with one or more non-optical elements, including a heat dissipation device such as a heat sink (or cooling fins), one or more adhesives (or fasteners), etc. In some implementations, the aperture 3002 may block and thus absorb approximately 15% of the incident light, and therefore the heat sink or cooling fins may be positioned and configured to appropriately dissipate heat from the aperture 3002. In some implementations, the aperture 3002 is thermally isolated from other portions of the projection lens system 3000.

[0099] The Fourier section 3001 and aperture 3002 collectively operate as a Fourier lens with a spatial filter that can also be used as a fixed throw projection lens. The zoom section 3003 shown in FIG. 30 may be one of a family of zoom lens assemblies configured to attach to the Fourier section 3001, thereby creating a family of projection zoom lens systems tailored to different theaters. In other words, the Fourier section 3001 and aperture 3002 may be applicable to any theater setting, but the zoom section 3003 provides a specific projection light pattern tailored to a particular theater. Therefore, by selecting a specific zoom section 3003 from a family of zoom lens assemblies and attaching the selected zoom section 3003 to the Fourier section 3001 and aperture 3002, a projection lens system 3000 tailored to a specific theater can be achieved. Additionally, both the Fourier section 3001 and the zoom section 3003 may include multiple individual lens elements.

[0100] The systems, methods, and devices according to the present disclosure may take any one or more of the following configurations:

[0101] (1) A projection system with pixel shifting, a light source configured to emit light; a spatial light modulator configured to receive light and generate modulated light, the spatial light modulator including a plurality of micromirrors; a wobulation device configured to shift the modulated light by a fractional pixel; a controller, for each of a plurality of sub-periods, controlling the light source to emit light onto the spatial light modulator; shifting the modulated light by a fractional pixel distance greater than a half pixel distance using a wobulation device during each of the plurality of subperiods; and a controller configured to:

[0102] (2) A projection system according to (1), a lens that spatially Fourier transforms the modulated light; a filter including an aperture that transmits at least one diffraction order of the modulated light that has been Fourier transformed by the lens and blocks the remainder of the modulated light; Further provided are:

[0103] (3) A projection system according to any one of (1) to (2), The plurality of sub-periods is four sub-periods.

[0104] (4) A projection system according to any one of (1) to (3), The fractional pixel distance is equal to a value ranging between 50.1% of the full pixel distance and 60% of the full pixel distance.

[0105] (5) A projection system according to any one of (1) to (4), The controller further shifting the modulated light by a distance greater than a half pixel distance in a first direction between a first sub-period and a second sub-period; shifting the modulated light by a distance greater than a half pixel distance in a second direction perpendicular to the first direction between the second sub-period and the third sub-period; shifting the modulated light by a distance greater than half a pixel distance in a third direction perpendicular to the second direction and opposite to the first direction between a third sub-period and a fourth sub-period; After a fourth sub-period, shifting the modulated light by a distance greater than a half pixel distance in a fourth direction perpendicular to the third direction and opposite to the second direction; It is structured as follows.

[0106] (6) A projection system according to any one of (1) to (5), the controller repeatedly causes the projection optics to emit the light and shift the modulated light for a plurality of image frames; It is structured as follows.

[0107] (7) A projection system according to any one of (1) to (6), a prism configured to receive light from the light source and redirect the light to a second light; The spatial light modulator receives the second light.

[0108] (8) A projection system according to any one of (1) to (7), The light source is a rectangular optical fiber.

[0109] (9) A method for calibrating pixel shift in a projection system, comprising: emitting light using a light source; receiving light using a spatial light modulator; modulating light with a spatial light modulator to generate a modulated image, the modulated image comprising a plurality of pixels; shifting the modulated light for each pixel of the modulated image by a fractional pixel distance during each of a plurality of sub-periods to generate a wobulated image; determining the amount of wobulation artifacts in the wobulated image; adjusting the fractional pixel distance based on the determined amount of wobulation artifacts; Includes.

[0110] (10) A method according to (9), Adjusting the fractional pixel distance includes adjusting the fractional pixel distance to be greater than the half pixel distance.

[0111] (11) A method according to any one of (9) to (10), The fractional pixel distance is adjusted by receiving input from a user interface.

[0112] (12) A method according to any one of (9) to (11), The frame rate of the projection system is kept constant during the step of adjusting the fractional pixel distance.

[0113] (13) A method according to any one of (9) to (12), The step of adjusting the fractional pixel distance depends on the frame rate of the projection system.

[0114] (14) A method according to any one of (9) to (13), The step of adjusting the fractional pixel distance includes adjusting the fractional pixel distance based on a model stored in memory.

[0115] (15) A projection method for pixel shifting, comprising: For each of a plurality of sub-periods, controlling a light source to emit light onto a plurality of micromirrors on a spatial light modulator; receiving light and generating modulated light for each of a plurality of sub-periods using a plurality of micromirrors; shifting the modulated light a fractional pixel distance greater than a half pixel distance between each of a plurality of subperiods; Includes.

[0116] (16) A projection method according to (15), spatially Fourier transforming the modulated light with a lens; using a filter having an aperture to transmit at least one diffraction order of the modulated light that has been Fourier transformed by the lens; blocking the remaining portion of the modulated light with a filter; Further includes:

[0117] (17) A projection method according to any one of (15) to (16), The plurality of sub-periods is four sub-periods.

[0118] (18) A projection method according to any one of (15) to (17), The fractional pixel distance is equal to a value ranging between 50.1% of the full pixel distance and 60% of the full pixel distance.

[0119] (19) A projection method according to any one of (15) to (18), shifting the modulated light in a first direction by a distance greater than a half pixel distance between a first sub-period and a second sub-period; shifting the modulated light by a distance greater than a half pixel distance in a second direction perpendicular to the first direction between a second sub-period and a third sub-period; shifting the modulated light by a distance greater than a half pixel distance in a third direction perpendicular to the second direction and opposite to the first direction between a third sub-period and a fourth sub-period; After the fourth sub-period, shifting the modulated light by a distance greater than a half pixel distance in a fourth direction perpendicular to the third direction and opposite to the second direction.

[0120] (20) A projection method according to any one of (15) to (19), The method further includes repeating the emitting of light and shifting the modulated light for a plurality of image frames.

[0121] (21) A projection method according to any one of (15) to (20), receiving light from a light source using a prism; redirecting the light into a second light using a prism; and receiving the second light with the spatial light modulator.

[0122] (22) A projection system with pixel shifting, a light source configured to emit light; a spatial light modulator configured to receive light and generate modulated light, the spatial light modulator comprising: a spatial light modulator including a plurality of micromirrors; a wobulation device configured to shift the modulated light by a fractional pixel; a controller, the controller for each of a plurality of sub-periods, controlling the light source to emit the light onto the spatial light modulator; During each of the plurality of sub-periods, and using a wobulation device, Controlling multiple micromirrors to an off position; Shifting the modulated light by a fractional pixel distance; The plurality of micromirrors are configured to be controlled to an ON position after the modulated light has been shifted by a fractional pixel distance.

[0123] (23) A projection system according to (22), The plurality of sub-periods is four sub-periods.

[0124] (24) A projection system according to any one of (22) to (23), The fractional pixel distance is equal to the half pixel distance.

[0125] (25) A projection system according to any one of (22) to (24), a lens that spatially Fourier transforms the modulated light; 1. A filter including an aperture, transmitting at least one diffraction order of the Fourier transformed modulated light by the lens; a filter that blocks the remainder of the modulated light; and Further provided are:

[0126] (26) A projection system according to any one of (22) to (25), The micromirrors are controlled to the off position for a duration of 5% to 25% of the duration of each sub-period.

[0127] (27) A projection system according to any one of (22) to (26), When in the off position, the plurality of micromirrors are configured to direct light to a light dump.

[0128] (28) A projection system according to any one of (22) to (27), The controller further shifting the modulated light by a distance greater than a half pixel distance in a first direction between a first sub-period and a second sub-period; shifting the modulated light by a distance greater than a half pixel distance in a second direction perpendicular to the first direction between the second sub-period and the third sub-period; shifting the modulated light by a distance greater than a half pixel distance in a third direction perpendicular to the second direction and opposite to the first direction between the third sub-period and the fourth sub-period; After a fourth sub-period, shifting the modulated light by a distance greater than a half pixel distance in a fourth direction perpendicular to the third direction and opposite to the second direction; It is structured as follows.

[0129] (29) A projection system according to any one of (22) to (28), wherein the controller repeatedly causes the projection optical system to emit the light and shift the modulated light for a plurality of image frames.

[0130] With respect to the processes, systems, methods, heuristics, etc. described herein, although steps of such processes, etc. are described as occurring according to a certain ordered sequence, it should be understood that such processes may be practiced with the described steps occurring in an order other than the order described herein. Furthermore, it should be understood that certain steps may be performed simultaneously, other steps may be added, or certain steps described herein may be omitted. In other words, the process descriptions herein are provided for the purpose of illustrating particular embodiments and should not be construed as limiting the scope of the claims in any way.

[0131] Therefore, it should be understood that the above description is intended to be illustrative, and not limiting. Many embodiments and applications other than the examples provided will be apparent from reading the above description. The scope should not be determined with reference to the above description, but instead should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technology described herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In short, it should be understood that this application is capable of modification and variation.

[0132] All terms used in the claims are intended to be given their broadest reasonable interpretation and their ordinary meaning as understood by one skilled in the art described herein, unless expressly indicated to the contrary herein. In particular, the use of singular articles such as "a," "the," "said," etc., should be read as referring to one or more of the indicated elements unless the claim states an express limitation to the contrary.

[0133] The Abstract of the present disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the claimed embodiments incorporate more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as separately claimed subject matter.

Claims

1. 1. A projection system with pixel shifting, comprising: a light source configured to emit light; a spatial light modulator configured to receive the light and generate modulated light, the spatial light modulator including a plurality of micromirrors; a wobulation device configured to shift the modulated light by a fractional pixel; a controller configured to control the light source to emit the light onto the spatial light modulator for each of a plurality of sub-periods, and to shift the modulated light by a fractional pixel distance greater than a half pixel distance using the wobulation device between each of the plurality of sub-periods; A system comprising:

2. a lens that spatially Fourier transforms the modulated light; a filter including an aperture that transmits at least one diffraction order of the modulated light that has been Fourier transformed by the lens and blocks the remaining portion of the modulated light; The system of claim 1 further comprising:

3. the plurality of sub-periods is four sub-periods; 3. The system according to claim 1 or 2.

4. the fractional pixel distance is equal to a value in the range between 50.1% of the total pixel distance and 60% of the total pixel distance; The system of claim 1 .

5. The controller shifting the modulated light by a distance greater than a half pixel distance in a first direction between a first sub-period and a second sub-period; shifting the modulated light by a distance greater than a half pixel distance in a second direction perpendicular to the first direction between the second sub-period and a third sub-period; shifting the modulated light by a distance greater than a half pixel distance in a third direction perpendicular to the second direction and opposite to the first direction between the third sub-period and the fourth sub-period; and after the fourth sub-period, shifting the modulated light by a distance greater than a half pixel distance in a fourth direction perpendicular to the third direction and opposite to the second direction. The system of claim 1 .

6. the controller repeatedly causes the projection system to emit the light and shift the modulated light for a plurality of image frames; The system of claim 1 .

7. and a prism configured to receive the light from the light source and redirect the light into a second light, the spatial light modulator receiving the second light. The system of claim 1 .

8. the light source is a rectangular optical fiber; The system of claim 1 .

9. 1. A method for calibrating pixel shift in a projection system, comprising: emitting light using a light source; receiving the light with a spatial light modulator; modulating the light with the spatial light modulator to generate a modulated image, the modulated image comprising a plurality of pixels; shifting the modulated light for each pixel of the modulation image by a fractional pixel distance during each of a plurality of sub-periods to generate a wobulated image; determining the amount of wobulation artifacts in the wobulation image; adjusting the fractional pixel distance based on the determined amount of wobulation artifacts; A method comprising:

10. adjusting the partial pixel distance includes adjusting the partial pixel distance to be greater than a half pixel distance; 10. The method of claim 9.

11. the fractional pixel distance is adjusted by receiving input from a user interface.

11. The method according to claim 9 or 10.

12. the frame rate of the projection system is kept constant during the step of adjusting the fractional pixel distance; 10. The method of claim 9.

13. adjusting the fractional pixel distance is dependent on a frame rate of the projection system; 10. The method of claim 9.

14. adjusting the fractional pixel distance includes adjusting the fractional pixel distance based on a model stored in a memory.

10. The method of claim 9.

15. A projection method for pixel shifting, comprising: For each of a plurality of sub-periods, controlling a light source to emit light onto a plurality of micromirrors on a spatial light modulator; receiving the light and generating modulated light for each of the plurality of sub-periods using the plurality of micromirrors; shifting the modulated light a fractional pixel distance greater than a half pixel distance between each of the plurality of subperiods; A method comprising:

16. spatially Fourier transforming the modulated light with a lens; using a filter having an aperture to transmit at least one diffraction order of the modulated light that has been Fourier transformed by the lens; and blocking a remaining portion of the modulated light with the filter.

16. The method of claim 15.

17. the plurality of sub-periods is four sub-periods; 17. The method according to claim 15 or 16.

18. the fractional pixel distance is equal to a value in the range between 50.1% of the total pixel distance and 60% of the total pixel distance; 16. The method of claim 15.

19. shifting the modulated light in a first direction by a distance greater than a half pixel distance between a first sub-period and a second sub-period; shifting the modulated light by a distance greater than a half pixel distance in a second direction perpendicular to the first direction between the second sub-period and a third sub-period; shifting the modulated light by a distance greater than a half pixel distance in a third direction perpendicular to the second direction and opposite to the first direction between the third sub-period and a fourth sub-period; after the fourth sub-period, shifting the modulated light by a distance greater than a half pixel distance in a fourth direction perpendicular to the third direction and opposite to the second direction.

16. The method of claim 15.

20. and repeating the emitting of the light and the shifting of the modulated light for a plurality of image frames.

16. The method of claim 15.

21. receiving the light from the light source with a prism; redirecting the light into a second light using the prism; receiving the second light using the spatial light modulator; 16. The method of claim 15.

Images