Upstream pixel shifting in projection systems

Abstract

A projection system for pixel shifting comprising a light source configured to emit light and a spatial light modulator configured to receive the light and generate a modulated light. The spatial light modulator includes a plurality of micromirrors. The projection system includes a wobulation device situated between the light source and the spatial light modulator. The wobulation device is configured to shift the light from the light source by fractional pixels. The projection system includes a controller configured to, for each of a plurality of subperiods, control the light source to emit the light onto the spatial light modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

Description

UPSTREAM PIXEL SHIFTING IN PROJECTION SYSTEMSCross-Reference to Related Applications

[0001] This application claims the benefit of priority from U.S. Provisional Application No. 63 / 562,552, filed on 7 March 2024, and European Application No. 24162023.6 filed on 7 March 2024, each of which is incorporated by reference herein in its entirety.Field of the Disclosure

[0002] This application relates generally to projection systems and projection methods.Description of Related Art

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

[0004] Some projection systems are based on SLMs that implement a spatial amplitude modulation, such as a digital micromirror device (DMD) chip or a liquid crystal on silicon (LCOS) chip. A DMD may utilize a two-dimensional array of mirrors which can be controlled to create an image. If one desires to project an image with a higher resolution than that of the DMD (e.g., an image having a greater number of pixels than the number of mirrors in the DMD), pixel-shifting techniques may be used. In one comparative example of a pixel-shifting technique, sometimes called “wobulation,” the system may be controlled to effectively shift the modulator, or a device situated optically after the modulator, by fractional pixels in a set pattern to create the appearance of displaying additional pixels.BRIEF SUMMARY OF THE DISCLOSURE

[0005] Wobulation devices are used to implement the pixel- shifting technique. Wobulation devices, or wobulators, are devices that move pixels rapidly between a set of fixed positions to create a highresolution image. For example, a wobulator may move pixels in a square pattern to quadruple the displayed resolution, creating a 2x2 set of pixels for each physical DMD pixel.

[0006] Wobulation devices are often implemented via an actuator and are situated after a primary modulator and before a projection lens. The actuator shifts the image in sub-pixel increments over time. While widespread, this technique requires a very compact, thin, and transmissive actuator due to space constrains between the primary modulator and the projection lens.

[0007] Embodiments described herein provide for performing pixel- shifting or wobulation techniques that implement a wobulation device before or at a modulation device. In the optical path before the modulator, there is far more space and fewer constraints on the size of the wobulation device. By placing the wobulation device before the modulator, actuators that arc not transmissive may instead be implemented, such as a tilting mirror.

[0008] In one example, a dual-modulation system is provided having a spatial light-steering modulator and an amplitude modulator. The spatial light-steering modulator is used at least in part to perform the function of tilting the illumination from a light source onto the amplitude modulator.

[0009] In another example, a modulation system is provided that includes a spatial light- steering modulator. The spatial light-steering modulator may be the only modulator in the modulation system or may be the last modulator in a dual-modulation system. The spatial light- steering modulator steers received light such that intermediate pixel positions are achieved in the image output by the spatial light-steering modulator.

[0010] In one example aspect of the present disclosure, there is provided a projection system with pixel shifting comprising a light source configured to emit a light, a modulator configured to receive the light and generate a modulated light, a wobulation device situated between the light source and the modulator, and a controller. The wobulation device is configured to shift the light from the light source by fractional pixels. The controller is configured to control, for each of a plurality of subperiods, the light source to emit the light onto the modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

[0011] In another example aspect of the present disclosure, there is provided a projection system with pixel shifting comprising a light source configured to emit a light, a first modulator configuredto receive the light and generate a first modulated light, and a second modulator configured to receive the first modulated light and generate a second modulated light. The first modulator includes a first plurality of micromirrors, and the second modulator includes a second plurality of micromirrors. The projection system also includes a wobulation device situated between the first modulator and the second modulator, and a controller. The wobulation device is configured to shift the first modulated light by fractional pixels. The controller is configured to control, for each of a plurality of subperiods, the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the first modulated light by a partial pixel distance.

[0012] In another example aspect of the present disclosure, there is provided a projection system with pixel shifting comprising a light source configured to emit a light, a first modulator configured to receive the light and generate a first modulated light, and a second modulator configured to receive the first modulated light and generate a second modulated light. The first modulator includes a first plurality of micromirrors and the second modulator includes a second plurality of micromirrors. The projection system also includes a wobulation device situated between the light source and the first modulator, and a controller. The wobulation device is configured to shift the light from the light source by fractional pixels. The controller is configured to control, for each of a plurality of subperiods, the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

[0013] In this manner, various aspects of the present disclosure provide for the display of images having a high dynamic range, high contrast ratio, and high resolution, and effect improvements in at least the technical fields of image projection, holography, signal processing, and the like.DESCRIPTION OF THE DRAWINGS

[0014] These and other more detailed and specific features of various embodiments are more fully disclosed in the following description, reference being had to the accompanying drawings, in which;

[0015] FIGS. 1A-1B illustrate views of an exemplary spatial light modulator according to various aspects of the present disclosure;

[0016] FIG. 2 illustrates an exemplary pixel-shift operation according to various aspects of the present disclosure;

[0017] FIG. 3 illustrates a block diagram of an exemplary projection system according to various aspects of the present disclosure;

[0018] FIGS. 4A-4B illustrate an object plane within an exemplary optical system according to various aspects of the present disclosure;

[0019] FIG. 5 illustrates a graph of the illumination angle at a modulator compared to the modulator object plane offset according to various aspects of the present disclosure;

[0020] FIG. 6 illustrates a block diagram of another exemplary projection system according to various aspects of the present disclosure;

[0021] FIG. 7 illustrates a block diagram of another exemplary projection system according to various aspects of the present disclosure; and

[0022] FIG. 8 illustrates an exemplary process flow of an exemplary pixel-shift method according to various aspects of the present disclosure.DETAILED DESCRIPTION

[0023] This disclosure and aspects thereof can be embodied in various forms, including hardware, devices, or circuits controlled by computer-implemented methods, computer program products, computer systems and networks, user interfaces, and application programming interfaces; as well as hardware-implemented methods, signal processing circuits, memory arrays, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and the like. The foregoing summary is intended solely to give a general idea of various aspects of the present disclosure, and does not limit the scope of the disclosure in any way.

[0024] In the following description, numerous details are set forth, such as optical device configurations, timings, operations, and the like, in order to provide an understanding of one or more aspects of the present disclosure. It will be readily apparent to one skilled in the art that these specific details are merely exemplary and not intended to limit the scope of this application.

[0025] Moreover, while the present disclosure focuses mainly on examples in which the various circuits are used in digital projection systems, it will be understood that this is merely one example of an implementation. It will further be understood that the disclosed systems and methods can be used in any device in which there is a need to project light; for example, cinema, consumer and other commercial projection systems, heads-up displays, virtual reality displays, and the like.

[0026] Pixel Shifting

[0027] The optics of a projection system utilizing a spatial light modulator (SLM) may be broadly categorized into two parts: the optics located on the illumination side ( / .<?., optically upstream of the SLM) and the optics located on the projection side (z.e., optically downstream of the SLM). The SLM itself includes a plurality of modulating elements arranged in, for example, a two-dimensional array. Individual modulating elements receive light from the illumination optics and convey light to the projection optics. In some examples, the SLM may be implemented as a digital micromirror device (DMD) chip; this will be discussed in more detail below. Generally, however, a DMD includes a two-dimensional array of reflective elements (micromirrors or simply “mirrors”) which selectively reflect light towards the projection optics or discard light based on the position of the individual reflective elements.

[0028] FIGS. 1A-1B illustrate various views of an exemplary DMD 100 according to various aspects of the present disclosure. In particular, FIG. 1A illustrates a plan view of the DMD 100 and FIG. IB illustrates a partial cross-sectional view of the DMD 100 taken along line I-B illustrated in FIG. 1 A. The DMD 100 includes a plurality of square micromirrors 102 arranged in a two- dimensional rectangular array on a substrate 104. In some examples, the DMD 100 may be a digital light processor (DLP) device. Each micromirror 102 may correspond to one pixel of the eventual projection image, and may be configured to tilt about a rotation axis 108, shown for one particular subset of the micromirrors 102, by electrostatic or other actuation. The individual micromirrors 102 have a width 112 and are arranged with gaps of width 110 therebetween. The micromirrors 102 may be formed of or coated with any highly reflective material, such as aluminum or silver, to thereby specularly reflect light. The gaps between the micromirrors 102 may be absorptive, such that input light which enters a gap is absorbed by the substrate 104.

[0029] While FIG. 1A expressly shows only some representative micromirrors 102, in practice the DMD 100 may include many more individual micromirrors. The resolution of the DMD 100 refersto the number of micromirrors in the horizontal and vertical directions. In some examples, the resolution may be 2K (2048x1080), 4K (4096x2160), 1080p (1920x1080), consumer 4K (3840x2160), and the like. Moreover, in some examples the micromirrors 102 may be rectangular and arranged in the rectangular array; hexagonal and arranged in a hexagonal array, and the like. Moreover, while FIG. 1A illustrates the rotation axis 108 extending in an oblique direction, in some implementations the rotation axis 108 may extend vertically or horizontally.

[0030] As can be seen in FIG. IB, each micromirror 102 may be connected to the substrate 104 by a yoke 114, which is rotatably connected to the micromirror 102. The substrate 104 includes a plurality of electrodes 116. While only two electrodes 116 per micromirror 102 are visible in the cross-sectional view of FIG. IB, each micromirror 102 may in practice include additional electrodes. While not particularly illustrated in FIG. IB, the DMD 100 may further include spacer layers, support layers, hinge components to control the height or orientation of the micromirror 102, and the like. The substrate 104 may include electronic circuitry associated with the DMD 100, such as CMOS transistors, memory elements, and the like.

[0031] Depending on the particular operation and control of the electrodes 116, the individual micromirrors 102 may be switched between an “on” position, an “off’ position, and an unactuated or neutral position. If a micromirror 102 is in the on position, it is actuated to an angle of, e.g., -12° (that is, rotated counterclockwise by 12° relative to the neutral position) to specularly reflect input light 106 into on-state light 118. If a micromirror 102 is in the off position, it is actuated to an angle of, e.g., +12° (that is, rotated clockwise by 12° relative to the neutral position) to specularly reflect the input light 106 into off-state light 120. The off-state light 120 may be directed toward a light dump that absorbs the off-state light 120. In some instances, a micromirror 102 may be unactuated and lie parallel to the substrate 104. The particular angles illustrated in FIGS. 1A-1B and described here are merely exemplary and not limiting. In some implementations, the on- and off-position angles may be between ±12 and ±13 degrees (inclusive), respectively.

[0032] In some implementations, the resolution of the DMD 100 may be lower than the desired resolution of the projected image. For example, one may desire to project an image having a 4K resolution, but DMDs having a 4K resolution may have limited or no commercial availability, prohibitive costs, and so on. In such implementations, it may be possible to control the 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 mirrorarray may be controlled to display a consumer 4K projected image. Pixel-shift techniques may be used to affect this control.

[0033] One exemplary pixel-shift technique (wobulation) uses some method (e.g., an optical method) to effectively shift the DMD 100 by fractional pixels in a set pattern to display additional pixels. One example of such a pixel- shift technique is illustrated in FIG. 2. In the pixel- shift technique of FIG. 2, a frame display period T (generally one divided by the projector frame rate) is divided into four sub-periods each having a duration of T / 4. At a time to corresponding to the start of the first sub-period and thus the staid of the frame display period T, an image is projected onto the screen. In FIG. 2, only a 2x2 subset of the pixels in the first resulting image 201 are shown; however, the first resulting image 201 in practice has a resolution corresponding to the relatively- lower resolution of the DMD 100. At a time ti corresponding to the start of the second sub-period, the image is shifted a half-pixel to the right, thus generating the second resulting image 202 on the screen. At a time t2 corresponding to the start of the third sub-period, the image is shifted a half-pixel down, thus generating the third resulting image 203 on the screen. At a time t3 corresponding to the start of the fourth sub-period, the image is shifted a half-pixel left, thus generating the fourth resulting image 204 on the screen. At the end of the frame display period T, the image may be shifted a half-pixel up, thus corresponding to the original position to begin 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 shifting is not limited to the column and row directions of the pixel array (z.e., up, down, left, and right), but may instead be in an oblique direction (e.g., diagonal). Moreover, while FIG. 2 shows a pixel- shifting technique which shifts the image in two dimensions, in certain implementations pixel- shifting may only occur in one dimension in a back-and-forth manner. Additionally, while shifting the light may imply simply moving the light, shifting the light may include tilting (e.g., changing the angle of) the light to change the direction of the light on an output image.

[0034] In some instances, a wobulation device performs the pixel- shifting on the output of the DMD 100, allowing the superimposed outputs of the DMD 100 to be viewed as a higher resolution output. The wobulation device is situated optically following the DMD 100, such that an output of the DMD 100 is received as an input of the wobulation device. The wobulation device may shift in a single direction (e.g., doubling the vertical resolution only or doubling the horizontal resolution only), or along multiple axes, such as a 2x2 position setup that doubles the resolution along both axes andeffectively quadrupling the number of output pixels. In some instances, the wobulation device may also follow a periodic continuous path, as opposed to a discrete 2x2 path with four “stops”. The wobulation device may also follow a quasi-random path.

[0035] Projector Systems

[0036] Some projection systems are based on SLMs that implement a spatial amplitude modulation. In such a system, the light source may provide a light field that embodies the brightest level that can be reproduced on the image, and light is attenuated or discarded in order to create the desired scene levels. Some high contrast examples of projection systems based on this architecture use a semicollimated illumination system and Fourier stop in the projection optics to improve contrast. An example of a projector or other display system including or relating to a Fourier plane and aperture have been described in commonly-owned patents and patent applications, including WIPO Pub. No. 2019 / 195182, titled “Systems and Methods for Digital Laser Projection with Increased Contrast Using Fourier Filter,” the contents of which are herein incorporated by reference in their entirety.

[0037] FIG. 3 illustrates an exemplary high contrast projection system 300 according to various aspects of the present disclosure. In particular, FIG. 3 illustrates a projection system 300 which includes a light source 301 configured to emit a first light 302; illumination optics 303 configured to receive the first light 302 and redirect or otherwise modify it, thereby to generate a second light 304; a wobulation device 305 configured to receive the second light 304 and shift the light, thereby to generate third light; a DMD 307 configured to receive the third light 306 and selectively redirect and / or modulate it as a fourth light 308; first projection optics 309 configured to receive the fourth light 308 and redirect or otherwise modify it, thereby to generate fifth light 310; a filter 311 configured to filter the fifth light 310, thereby to generate a sixth light 312; and second projection optics 313 configured to receive the sixth light 312 and project it as a seventh light 314 onto a screen 315. The DMD 307 may be the same as or similar to the DMD 100 illustrated in FIGS. 1A-1B. The first projection optics 309 may include at least one lens configured to spatially Fourier transform the fourth light 308 onto a plane (also referred to as the Fourier plane). The filter 311 may be a Fourier aperture (also referred to as a Fourier filter); that is, an aperture located at or near the plane at which a Fourier transform of an object is formed. Micromirrors and gaps of the DMD 307 may cooperate to form a two-dimensional grating that diffracts input light. Therefore, modulated light propagating away from DMD 307 may form a plurality of diffraction orders observable as a Fraunhofer diffraction pattern in a far- field region of DMD 307 or at a focal plane of a lens. Each diffractionorder corresponds to one light beam propagating away from DMD 307 in a unique respective direction.

[0038] While FIG. 3 illustrates the first projection optics 309, the filter 311, and the second projection optics 313 as separate entities, in some implementations the filter 311 may be incorporated as part of a larger optical system including the first projection optics 309 and the second projection optics 3411. Various elements of the projection system 300 may be operated by or under the control of a controller 316; for example, one or more processors such as a central processing unit (CPU) of the projection system 300. As illustrated in FIG. 3, the light source 301, the wobulation device 305, and the DMD 307 are controlled by the controller 316. In some implementations, the controller 316 may additionally or alternatively control other components of the projection system 300, including but not limited to the illumination optics 303, the first projection optics 309, and / or the second projection optics 313. In one particular example, the controller 316 may control components of the illumination optics 303 to ensure the third light 306 is incident on the DMD 307 (through the wobulation device 305) at the appropriate location and / or angle.

[0039] In 3D or 3D-capable projection implementations, a physical projector may include two projection systems 300 disposed side-by-side, with each individual projection system 300 projecting an image corresponding to one eye of the viewer. Alternatively, a physical projector may utilize one combined projection system 300 to project individual images corresponding to both eyes of the viewer.

[0040] In some implementations, the projection system 300 may include fewer optical components or may include additional optical components such as mirrors, lenses, waveguides, optical fibers, beam splitters, diffusers, and the like. With the exception of the screen 315, the components illustrated in FIG. 3 may be integrated into a housing to provide a projection device. Such a projection device may include additional components such as a memory, input / output ports, communication circuitry, a power supply, and the like.

[0041] The light source 301 may be, for example, a laser light source, an LED, a light source coupled via one or more optical fibers, and the like. The first light 302 emitted by the light source 301 may be circular, rectangular, or square in shape. In some aspects of the present disclosure, the light source 301 may comprise multiple individual light emitters, each corresponding to a differentwavelength or wavelength band. The light source 301 emits light in response to an image signal provided by the controller 316. The image signal includes image data corresponding to a plurality of frames to be successively displayed. The image signal may originate from an external source in a streaming or cloud-based manner, may originate from an internal memory of the projection system 300 such as a hard disk, may originate from a removable medium that is operatively connected to the projection system 300, or combinations thereof.

[0042] In some instances, the projection system 300 achieves a high f-number having a narrow illumination angle while maintaining uniformity in the light illuminated onto the DMD 307. The f- number (denoted f / #) is the ratio of the system’s focal length to the diameter of the aperture. The f / # of the light passing through the first projection optics 309 may be, for example, between f / 9 and 1715. In some embodiments, the f-number of light passing through the first projection optics 309 is between f / 15 and f / 22. In some embodiments, the f-number of light passing through the first projection optics 309 is greater than f / 22.

[0043] This high f-number and high contrast of the projection system 300 enables the ability to locate the wobulation device 305 before the DMD 307. Traditionally, when the object plane of the imaging optics does not perfectly coincide with the modulator, then the illumination angle has an effect on the final image. In traditional systems, the f-number of the illumination may be relatively small, resulting in a shallow depth of focus. With an increased usage of laser architectures, the f- number of the illumination is increased which, in turn, increases the depth of focus. The displacements in object space to be achieved by the micromirrors 102 are usually small. For instance, for a 2048x1080 DLP modulator with a 10.8pm pitch, the required deflection is half the pitch in each axis of the modulator for a four-way actuator. The f-number of the illumination is independent from the pitch of device and thus independent of the deflection that needs to be achieved to increase resolution.

[0044] However, modulators are gridded devices and thus generate diffraction orders. While the depth of focus at high f-numbers can be very deep for some “main” diffraction order down the optical axis of the imaging optics, any defocus may cause the other diffraction orders to appear as offset “ghost” images. For example, FIG. 4A illustrates an example optical system 400 including the DMD 307, projection optics 401, and the screen 315. The optical system 400 represents a subset of components of the projection system 300. While the projection optics 401 is illustrated as a single optical component, the projection optics 401 may be, for example, the first projection optics309, the filter 311, the second projection optics 313, or a combination thereof. In the example of FIG. 4A, an object plane 402 is situated directly at the DMD 307. A first light beam 403 and a second light beam 404 are illustrated, the first light beam 403 having a different illumination angle than the second light beam 404. Although the first light beam 403 and the second light beam 404 have different illumination angles, as the object plane 402 is aligned with the DMD 307, the first light beam 403 and the second light beam 404 are still aligned at the screen 315.

[0045] However, moving the wobulation device 305 may result in a shift of the object plane 402 off the DMD 307 by a distance x, as shown in FIG. 4B. When the object plane 402 no longer aligns with the DMD 307, the illumination angle of light on the DMD 307 impacts the location of the light on the screen 315. For example, as shown in FIG. 4B, the first light beam 403 and the second light beam 404 do not align at the screen 315. Accordingly, the final image includes an amount of defocus. However, in systems with high f-numbers (e.g., high contrast), only a single diffraction order may be targeted, avoiding defocus caused by other diffraction orders.

[0046] FIG. 5 illustrates the relationship between the illumination angle at the modulator (A0) and the modulator object plane offset (Az). Particularly, the horizontal axis is displacement along the optical axis from the object plane 402. The curved line A (9 is related to the left vertical axis and illustrates the illumination tilt to achieve a half-pixel displacement for an upsampling factor of U=2. The upsampling factor indicates how much angle the upstream actuator induces in the illumination. The straight line S in FIG. 5 is related to the right vertical axis and indicates how the pixel size scales (i.e., how large the pixels become).

[0047] Embodiments described thus fa' have primarily referred to projection systems having a single modulator. However, wobulation techniques described herein may also be implemented in multi-modulation systems. For example, FIG. 6 illustrates a projection system 600 having both a first modulation device 601 and a second modulation device 604. The second modulation device 604 may be, for example, the DMD 307. The first modulation device 601 may be the same as or similar to the DMD 100 illustrated in FIGS. 1A-1B. Besides having two modulation devices, the projection system 600 is substantially similar to the projection system 300. In the example of FIG. 6, wobulation device 305 is situated between the first modulation device 601 and the second modulation device 604.

[0048] The first modulation device 601 is configured to receive the second light 304 from the illumination optics 303 and selectively redirect and / or modulate it as a third light 602. The wobulation device 305 receives the third light 602 and shifts the light, thereby to generate a fourth light 603. The second modulation device 604 is configured to receive the fourth light 603 and selectively redirect and / or modulate it as a fifth light 605. The fifth light 605 is received by the first projection optics 309.

[0049] In some instances, the wobulation device 305 may be situated before both modulators in a dual-modulation system. For example, FIG. 7 illustrates another projection system 700 having both a first modulation device 701 and a second modulation device 703. The first modulation device 701 and the second modulation device 703 may each be the same as or similar to the DMD 100 illustrated in FIGS. 1A-1B. Besides having two modulation devices, the projection system 700 is substantially similar to the projection system 300. In the example of FIG. 7, the wobulation device 305 is situated before the first modulation device 701. The wobulation device 305 receives the second light 304 from the illumination optics 303 and shifts the light, thereby to generate third light 306. The first modulation device 701 is configured to receive the third light 306 and selectively redirect and / or modulate it as a fourth light 702. The second modulation device 703 is configured to receive the fourth light 702 and selectively redirect and / or modulate it as a fifth light 704. The fifth light 704 is received by the first projection optics 309. In some embodiments, additional optical components may be situated between the first modulation device 701 and the second modulation device 703.

[0050] Pixel Shifting Techniques

[0051] One particular implementation of a pixel-shift technique in a projection system, such as the projection system 300 illustrated in FIG. 3, is illustrated in FIG. 8. the method 800 of FIG. 8 may be performed by the controller 316 of FIG. 3, and may be implemented using hardware, software, firmware, or combinations thereof. In some examples, the method 800 is implemented as instructions stored in a non-transitory computer-readable medium, such as a hard disk, or other storage medium contained in or associated with the projection system 300.

[0052] In the method 800, a series of images are displayed using image data which includes a series of frames. The image data is divided into a plurality of frame periods each corresponding to the duration T of a frame; for example, a 60 Hz display has a frame period T of (1 / 60) sec. At operation801, the frame period is divided into N subperiods, with N being an integer larger than 1. Preferably, N is four to implement a pixel-shifting pattern similar to that illustrated in FIG. 2; however, in other implementations N may be six or another number other than four. At operation802, a counter 1 is initialized to 1. Subsequently, at operation 803, an image is projected through the filter aperture for the Ithsubperiod. Operation 803 may include sub-operations, such as causing a light source of the projection system to emit light, controlling the spatial light modulator (e.g., the DMD 307 of FIG. 3) to modulate the light and form the image, and so on. This image is maintained for a duration of T / N. In the example of a 60 Hz display using four subperiods per frame, this subperiod duration is (1 / 240) sec.

[0053] At the end of the subperiod at operation 804, the counter I is compared to N to determine if the subperiod is the last subperiod of the frame. If the counter I does not equal N, at operation 805 the counter I is incremented by 1 and at operation 806 the pixels are shifted. In the example where four subperiods are provided per frame and the pixel- shifting follows a square pattern as in FIG. 2, this corresponds to a half-pixel shift. Alternatively, four subperiods may be provided per frame and the pixel- shifting may follow a diamond or rectangle pattern; six subperiods may be provided per frame and the pixel- shifting may follow a rectangle or hexagon pattern; three subperiods may be provided per frame and the pixel-shifting may follow a triangle pattern; two subperiods may be provided per frame and the pixel-shifting may follow a linear (back-and-forth) pattern; and so on. In some implementations, the number of subperiods may be on the order of tens (or greater) and the pixel-shifting may approximate a circular pattern or a complex shape. Thereafter, operation 803 is repeated for the next subperiod until the time when the counter I is equal to N. At this point, at operation 807 the frame is incremented and the method 800 returns to operation 807. Operations 802 through 807 are repeated for the duration of image display, and may continue until the endpoint of the media content has been reached, an operation issues a pause or stop instruction, and so on.

[0054] Systems, methods, and devices in accordance with the present disclosure may take any one or more of the following configurations.

[0055] (1) A projection system with pixel shifting, comprising: a light source configured to emit a light; a modulator configured to receive the light and generate a modulated light; a wobulation device situated between the light source and the modulator, the wobulation device configured to shift the light from the light source by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the modulator, and betweeneach of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

[0056] (2) The projection system according to (1), further comprising: a lens configured to spatially Fourier transform the modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the modulated light as Fourier-transformed by the lens and to block a remaining portion of the modulated light.

[0057] (3) The projection system according to any one of (1) to (2), wherein the plurality of subperiods is four subperiods.

[0058] (4) The projection system according to any one of (1) to (3), wherein the modulated light has an f-number greater than or equal to f / 15.

[0059] (5) The projection system according to (4), wherein the modulated light has an f-number greater than or equal to f / 22.

[0060] (6) The projection system according to any one of (1) to (5), wherein the controller is configured to: between a first subperiod and a second subperiod, shift the light in a first direction, between the second subperiod and a third subperiod, shift the light in a second direction perpendicular to the first direction, between the third subperiod and a fourth subperiod, shift the light in a third direction perpendicular to the second direction and opposite to the first direction, and after the fourth subperiod, shift the light in a fourth direction perpendicular to the third direction and opposite to the second direction.

[0061] (7) The projection system according to any one of (1) to (6), wherein the controller is configured to repeatedly cause the projection system to emit the light and shift the light for a plurality of image frames.

[0062] (8) The projection system according to any one of (1) to (7), wherein an object plane of the projection system is misaligned with the modulator.

[0063] (9) A projection system with pixel shifting, comprising: a light source configured to emit a light; a first modulator configured to receive the light and generate a first modulated light, wherein the first modulator includes a first plurality of micromirrors; a second modulator configured to receive the first modulated light and generate a second modulated light, wherein the secondmodulator includes a second plurality of micromirrors; a wobulation device situated between the first modulator and the second modulator, the wobulation device configured to shift the first modulated light by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the first modulated light by a partial pixel distance.

[0064] (10) The projection system according to (9), further comprising: a lens configured to spatially Fourier transform the second modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the second modulated light as Fourier- transformed by the lens and to block a remaining portion of the second modulated light.

[0065] (11) The projection system according to any one of (9) to (10), wherein the second modulated light has an f-number greater than or equal to f / 15.

[0066] (12) The projection system according to (11), wherein the second modulated light has an f- number greater than or equal to f / 22.

[0067] (13) The projection system according to any one of (9) to (12), wherein the controller is configured to: between a first subperiod and a second subperiod, shift the first modulated light in a first direction, between the second subperiod and a third subperiod, shift the first modulated light in a second direction perpendicular to the first direction, between the third subperiod and a fourth subperiod, shift the first modulated light in a third direction perpendicular to the second direction and opposite to the first direction, and after the fourth subperiod, shift the first modulated light in a fourth direction perpendicular to the third direction and opposite to the second direction.

[0068] (14) The projection system according to any one of (9) to (13), wherein the controller is configured to repeatedly cause the projection system to emit the light and shift the first modulated light for a plurality of image frames.

[0069] (15) The projection system according to any one of (9) to (14), wherein an object plane of the projection system is misaligned with the second modulator.

[0070] (16) A projection system with pixel shifting, comprising: a light source configured to emit a light; a first modulator configured to receive the light and generate a first modulated light, wherein the first modulator includes a first plurality of micromirrors; a second modulator configured toreceive the first modulated light and generate a second modulated light, wherein the second modulator includes a second plurality of micromirrors; a wobulation device situated between the light source and the first modulator, the wobulation device configured to shift the light from the light source by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

[0071] (17) The projection system according to (16), further comprising: a lens configured to spatially Fourier transform the second modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the second modulated light as Fourier- transformed by the lens and to block a remaining portion of the second modulated light.

[0072] (18) The projection system according to any one of (16) to (17), wherein the second modulated light has an f-number greater than or equal to f / 15.

[0073] (19) The projection system according to (18), wherein the second modulated light has an f- number greater than or equal to f / 22.

[0074] (20) The projection system according to any one of (16) to (19), wherein an object plane of the projecting system is misaligned with the second modulator.

[0075] With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claims.

[0076] Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the application is capable of modification and variation.

[0077] All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

[0078] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, 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 is not to 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. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

Claims

CLAIMSWhat is claimed is:

1. A projection system with pixel shifting, comprising: a light source configured to emit a light; a modulator configured to receive the light and generate a modulated light; a wobulation device situated between the light source and the modulator, the wobulation device configured to shift the light from the light source by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

2. The projection system of claim 1, further comprising: a lens configured to spatially Fourier transform the modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the modulated light as Fourier-transformed by the lens and to block a remaining portion of the modulated light.

3. The projection system of claim 1 or 2, wherein the plurality of subperiods is four subperiods.

4. The projection system of any one of claims 1 to 3, wherein the modulated light has an f- number greater than or equal to f / 15.

5. The projection system of claim 4, wherein the modulated light has an f-number greater than or equal to f / 22.

6. The projection system of any one of claims 1 to 5, wherein the controller is configured to: between a first subperiod and a second subperiod, shift the light in a first direction,between the second subperiod and a third subperiod, shift the light in a second direction perpendicular to the first direction, between the third subperiod and a fourth subperiod, shift the light in a third direction perpendicular to the second direction and opposite to the first direction, and after the fourth subperiod, shift the light in a fourth direction perpendicular to the third direction and opposite to the second direction.

7. The projection system of any one of claims 1 to 6, wherein the controller is configured to repeatedly cause the projection system to emit the light and shift the light for a plurality of image frames.

8. The projection system of any one of claims 1 to 7, wherein an object plane of the projection system is misaligned with the modulator.

9. A projection system with pixel shifting, comprising: a light source configured to emit a light; a first modulator configured to receive the light and generate a first modulated light, wherein the first modulator includes a first plurality of micromirrors; a second modulator configured to receive the first modulated light and generate a second modulated light, wherein the second modulator includes a second plurality of micromirrors; a wobulation device situated between the first modulator and the second modulator, the wobulation device configured to shift the first modulated light by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the first modulated light by a partial pixel distance.

10. The projection system of claim 9, further comprising: a lens configured to spatially Fourier transform the second modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the second modulated light as Fourier-transformed by the lens and to block a remaining portion of the second modulated light.

11. The projection system of claim 9 or 10, wherein the second modulated light has an f- number greater than or equal to f / 15.

12. The projection system of claim 11, wherein the second modulated light has an f-number greater than or equal to f / 22.

13. The projection system of any one of claims 9 to 12, wherein the controller is configured to: between a first subperiod and a second subperiod, shift the first modulated light in a first direction, between the second subperiod and a third subperiod, shift the first modulated light in a second direction perpendicular to the first direction, between the third subperiod and a fourth subperiod, shift the first modulated light in a third direction perpendicular to the second direction and opposite to the first direction, and after the fourth subperiod, shift the first modulated light in a fourth direction perpendicular to the third direction and opposite to the second direction.

14. The projection system of any one of claims 9 to 13, wherein the controller is configured to repeatedly cause the projection system to emit the light and shift the first modulated light for a plurality of image frames.

15. The projection system of any one of claims 9 to 14, wherein an object plane of the projection system is misaligned with the second modulator.

16. A projection system with pixel shifting, comprising: a light source configured to emit a light; a first modulator configured to receive the light and generate a first modulated light, wherein the first modulator includes a first plurality of micromirrors; a second modulator configured to receive the first modulated light and generate a second modulated light, wherein the second modulator includes a second plurality of micromirrors;a wobulation device situated between the light source and the first modulator, the wobulation device configured to shift the light from the light source by fractional pixels; and a controller configured to: for each of a plurality of subperiods, control the light source to emit the light onto the first modulator, and between each of the plurality of subperiods and with the wobulation device, shift the light from the light source by a partial pixel distance.

17. The projection system of claim 16, further comprising: a lens configured to spatially Fourier transform the second modulated light; and a filter including an aperture, the filter configured to transmit at least one diffraction order of the second modulated light as Fourier-transformed by the lens and to block a remaining portion of the second modulated light.

18. The projection system of claim 16 or 17, wherein the second modulated light has an f- number greater than or equal to f / 15.

19. The projection system of claim 18, wherein the second modulated light has an f-number greater than or equal to f / 22.

20. The projection system of any one of claims 16 to 19, wherein an object plane of the projection system is misaligned with the second modulator.