Color Select Column

Abstract

A pixel driver is arranged to drive a display device to simultaneously display a first color pixel pattern and a second color pixel pattern on its pixel array. The pixel driver includes n data lanes and a pixel voltage selector. The n data lanes are respectively arranged to receive n consecutive pixel values of a row of pixel values of pixel data substantially simultaneously. The pixel voltage selector connects a first data lane of the n data lanes to a first color gamma buffer to retrieve a first analog voltage according to a first color calibration. The pixel voltage selector also connects a second data lane of the n data lanes to a second color gamma buffer to retrieve a second analog voltage according to a second color calibration. The association between the data lanes and the gamma buffers is dynamic or programmable.

Description

Technical Field

[0001] This disclosure relates to a display device, a pixel driver, and a pixel data stream. It also relates to a method for receiving pixel values ​​from multiple datasets of different colors in a common data stream. Furthermore, it relates to a spatially separated color display method. Background Technology

[0002] Light scattered from an object contains amplitude and phase information. This amplitude and phase information can be captured on, for example, a photosensitive plate using well-known interferometry techniques to form a holographic record or "hologram" containing interference fringes. The hologram can be reconstructed by illuminating it with appropriate light to form a two-dimensional or three-dimensional holographic reconstruction or replay image representing the original object.

[0003] Computer-generated holography can numerically simulate interference processes. Computer-generated holograms can be calculated using techniques based on mathematical transformations such as Fresnel or Fourier transforms. These types of holograms can be called Fresnel / Fourier transform holograms, or simply Fresnel / Fourier holograms. Fourier holograms can be viewed as a Fourier domain / plane representation or a frequency domain / plane representation of an object. Computer-generated holograms can also be calculated using coherent ray tracing or point cloud techniques.

[0004] Computer-generated holograms can be encoded on spatial light modulators arranged to modulate the amplitude and / or phase of incident light. Optical modulation can be achieved using electrically addressed liquid crystals, optically addressed liquid crystals, or micromirrors.

[0005] Spatial light modulators typically consist of multiple individually addressable pixels, also referred to as cells or elements. The light modulation scheme can be binary, multilevel, or continuous. Alternatively, the device can be continuous (i.e., not composed of pixels), allowing light modulation to occur continuously throughout the device. Spatial light modulators can be reflective, meaning the modulated light is output via reflection. Spatial light modulators can also be transmissive, meaning the modulated light is output via transmission.

[0006] The system described herein can be used to provide holographic projectors. Such projectors have been applied to head-up displays ("HUDs") and head-mounted displays ("HMDs"), including near-eye devices. Summary of the Invention

[0007] The aspects of this disclosure are defined in the appended independent claims.

[0008] A first aspect of this disclosure is a pixel driver arranged to drive a display device to simultaneously display a first color pixel pattern and a second color pixel pattern on its pixel array. The pixel driver includes n data channels and a pixel voltage selector. The n data channels are respectively arranged to receive n consecutive pixel values ​​of a row of pixel values ​​of pixel data at substantially the same time. The pixel voltage selector connects a first data channel of the n data channels to a first color gamma buffer to retrieve a first analog voltage according to a first color calibration of the pixels of the display device. The pixel voltage selector also connects a second data channel of the n data channels to a second color gamma buffer to retrieve a second analog voltage according to a second color calibration of the pixels of the display device. Optionally, every nth pixel value of the pixel data corresponds to the same color, but different channels correspond to different gamma buffers or colors. Alternatively, it can be said that every nth pixel value of the pixel data uses the same color calibration. The association between the data channels and the gamma buffers is dynamic or programmable. The n data channels can be understood as corresponding to columns of the pixel array.

[0009] The pixel voltage selector can also connect the third data channel of the n data channels to the third color gamma buffer in order to retrieve the third analog voltage according to the third color calibration.

[0010] The first color can be red, the second color can be blue, and the third color can be green.

[0011] The first, second, and third data channels can be consecutive data channels, corresponding to consecutive pixel values ​​of the pixel data.

[0012] The first, second, and third data channels may not be consecutive data channels, and the pixel voltage selector may connect the n data channels to gamma buffers of different colors in the following repeating order: first color, second color, third color, first color, second color, third color, first color, second color, third color, second color, third color.

[0013] The first, second, and third data lines may not be consecutive data channels, and the pixel voltage selector may connect the n data channels to gamma buffers of different colors in the following repeating order: first color, first color, first color, second color, second color, second color, third color, third color, third color.

[0014] The first, second, and third data channels may not be consecutive data channels, and the pixel voltage selector may connect the n data channels to gamma buffers of different colors in the following repeating order: third color, first color, first color, second color, first color, third color, second color, second color, third color.

[0015] The first, second, and third data channels may not be consecutive data channels, and the pixel voltage selector may connect the n data channels to gamma buffers of different colors in the following repeating order: third color, third color, third color, third color, third color, third color, third color, third color, third color, third color.

[0016] The pixel driver may also include a color selector arranged to dynamically determine the monochrome gamma buffer connected to each of the n data channels.

[0017] The color selector may include an I2C or register that assigns a monochrome gamma buffer to each data channel. Advantageously, instead of using messages in the video signal to select the gamma to be demultiplexed, a gamma buffer can be pre-selected for each column (i.e., data channel) during device setup (e.g., via I2C messages) and kept fixed until reprogramming. In contrast, conventional display technologies can use messages in the video signal to dynamically change the gamma buffer selection to select the gamma to be demultiplexed. The method disclosed herein is synergistic with holography, where images are reconstructed through diffraction, so each "image point" does not require red, green, and blue values. The inventors recognized that fixing the selection of gamma buffers for each column is uniquely advantageous for holographic applications, rather than for conventional display devices such as liquid crystal displays, due to this diffraction reconstruction. Therefore, those skilled in the art would not find it obvious that pre-selection of gamma buffers for pixel data columns is necessary.

[0018] When pixel values ​​are received on the n data channels, the color selector can assign a monochrome gamma buffer to each data channel.

[0019] The value of n can be in the range of 6 to 20, for example, 8 to 12.

[0020] Each pixel value in the pixel data can include at least 6 bits. Each pixel value can be a 6-bit or 8-bit binary number.

[0021] The display device may be a phase modulator. The display device may be a silicon-based liquid crystal spatial light modulator.

[0022] The term "hologram" is used to refer to a record containing amplitude or phase information about an object, or some combination thereof. The term "holographic reconstruction" is used to refer to the optical reconstruction of an object formed by illuminating a hologram. The system disclosed herein is described as a "holographic projector" because the holographic reconstruction is a real image and spatially separate from the hologram. The term "reproduction field" is used to refer to the two-dimensional region that forms the holographic reconstruction and is fully focused. If the hologram is displayed on a spatial light modulator containing pixels, the reproduction field will be repeated in the form of multiple diffraction orders, where each diffraction order is a copy of the zero-order reproduction field. The zero-order reproduction field typically corresponds to the preferred or dominant reproduction field because it is the brightest reproduction field. Unless explicitly stated otherwise, the term "reproduction field" should be understood to refer to the zero-order reproduction field. The term "reproduction plane" is used to refer to the spatial plane containing all reproduction fields. The terms "image," "reproduced image," and "image region" refer to the region of the reproduction field illuminated by the light from the holographic reconstruction. In some embodiments, an "image" may include discrete points that may be referred to as "image points" or, for convenience only, "image pixels".

[0023] The terms "encoding," "writing," or "addressing" are used to describe the process of providing a plurality of control values ​​to a plurality of pixels of an SLM, each of which determines the modulation level of the pixel. In other words, the pixels of an SLM are configured to "display" an optical modulation distribution in response to receiving the plurality of control values. Therefore, it can be said that an SLM "displays" a hologram, and the hologram can be viewed as an array of optical modulation values ​​or levels.

[0024] It has been discovered that acceptable-quality holographic reconstructions can be formed from "holograms" containing only phase information related to the Fourier transform of the original object. Such holographic records can be called pure phase holograms. The embodiments relate to pure phase holograms, but this disclosure is equally applicable to pure amplitude holography.

[0025] This disclosure is also applicable to forming holographic reconstructions using amplitude and phase information associated with the Fourier transform of the original object. In some embodiments, this is achieved through complex modulation using a so-called fully complex hologram containing amplitude and phase information associated with the original object. Such a hologram can be called a fully complex hologram because the value (gray level) assigned to each pixel of the hologram has both amplitude and phase components. The value (gray level) assigned to each pixel can be represented as a complex number having both amplitude and phase components. In some embodiments, the fully complex number is computed to generate the hologram.

[0026] The term "phase delay" can be a shorthand for the phase value, phase component, phase information, or simply phase of a pixel in a computer-generated hologram or spatial light modulator. That is, any phase value described is actually a number (e.g., in the range of 0 to 2π) that represents the amount of phase delay provided by that pixel. For example, a spatial light modulator pixel described as having a phase value of π / 2 would delay the phase of received light by π / 2 radians. In some embodiments, each pixel of a spatial light modulator can operate on one of a plurality of possible modulation values ​​(e.g., phase delay values). The term "gray level" can be used to refer to a plurality of available modulation levels. For example, the term "gray level" can be conveniently used to refer to a plurality of available phase levels in a pure phase modulator, even if different phase levels do not provide different shades of gray. The term "gray level" can also be conveniently used to refer to a plurality of available complex modulation levels in a complex modulator.

[0027] Therefore, a hologram comprises an array of gray levels—that is, an array of optical modulation values, such as an array of phase delay values ​​or a complex modulation value array. A hologram is also considered a diffraction pattern because it is a pattern that causes diffraction when displayed on a spatial light modulator and illuminated with light whose wavelength is comparable to, and typically smaller than, the pixel spacing of the spatial light modulator. This document relates to combining holograms with other diffraction patterns, such as those used as lenses or gratings. For example, a diffraction pattern used as a grating can be combined with a hologram to translate the playback field on the playback plane, or a diffraction pattern used as a lens can be combined with a hologram to focus the holographic reconstruction in the near field onto the playback plane.

[0028] Although different embodiments and groups of embodiments may be disclosed individually in the detailed description below, any feature of any embodiment or group of embodiments may be combined with any other feature or combination of features of any embodiment or group of embodiments. That is, all possible combinations and arrangements of features disclosed in this disclosure are contemplated. Attached Figure Description

[0029] Specific embodiments are described by way of example only with reference to the following figures:

[0030] Figure 1 This is a schematic diagram illustrating a reflective SLM that generates holographic reconstruction on a screen;

[0031] Figure 2A The first iteration of the example Gerchberg-Saxton type algorithm is shown;

[0032] Figure 2B The second and subsequent iterations of the example Gerchberg-Saxton type algorithm are shown;

[0033] Figure 2CThe second and subsequent iterations of the example Gerchberg-Saxton type algorithm are shown;

[0034] Figure 3 This is a schematic diagram of a reflective LCOS SLM;

[0035] Figure 4 Possible column assignments according to an embodiment are shown;

[0036] Figure 5 This shows how pixels in the data are mapped to pixels;

[0037] Figure 6 An example of demultiplexing gamma based on pixel values ​​at the array is shown; and

[0038] Figure 7 The color selection for each column according to the embodiment is shown.

[0039] The same reference numerals will be used throughout the accompanying drawings to refer to the same or similar parts. Detailed Implementation

[0040] This invention is not limited to the embodiments described below, but extends to the full scope of the appended claims. That is, the invention can be embodied in different forms and should not be construed as limited to the described embodiments, which are illustrated for illustrative purposes.

[0041] Unless otherwise stated, a singular term may include a plural term.

[0042] A structure described as being formed on or below another structure should be interpreted to include situations where the structures are in contact with each other, and also includes situations where a third structure is positioned between them.

[0043] When describing temporal relationships, such as when the chronological order of events is described as “after,” “following,” “next,” “before,” etc., this disclosure should be considered to include both consecutive and discontinuous events unless otherwise stated. For example, unless terms such as “only,” “immediately,” or “directly” are used, the description should be considered to include discontinuous cases.

[0044] Although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the appended claims, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0045] Features of different embodiments may be coupled or combined with each other in part or in whole, and may interoperate with each other in various ways. Some embodiments may be implemented independently of each other, or may be implemented together in an interdependent relationship.

[0046] Optical configuration

[0047] Figure 1 An embodiment is shown in which a computer-generated hologram is encoded on a single spatial light modulator. The computer-generated hologram is the Fourier transform of the object to be reconstructed. Thus, the hologram can be described as a Fourier domain, frequency domain, or spectral domain representation of the object. In this embodiment, the spatial light modulator is a reflective liquid crystal on silicon ("LCOS") device. The hologram is encoded on the spatial light modulator, and the holographic reconstruction is formed at the playback field, for example, a light-receiving surface such as a screen or diffuser.

[0048] A light source 110 (e.g., a laser or laser diode) is arranged to illuminate the SLM 140 through a collimating lens 111. The collimating lens causes a generally planar wavefront to be incident on the SLM. Figure 1 In this embodiment, the wavefront is oriented off-axis (e.g., two to three degrees away from a direction truly perpendicular to the plane of the transparent layer). However, in other embodiments, a generally planar wavefront is provided with normal incidence, and a beam splitter arrangement is used to separate the input and output optical paths. Figure 1 In the illustrated embodiment, the arrangement is such that light from the light source is reflected from the mirrored rear surface of the SLM and interacts with the light modulation layer to form an outgoing wavefront 112. The outgoing wavefront 112 is applied to an optics device including a Fourier transform lens 120, the focal point of which is at a screen 125. More specifically, the Fourier transform lens 120 receives the modulated beam from the SLM 140 and performs a frequency-space transformation to produce a holographic reconstruction at the screen 125.

[0049] It is noteworthy that in this type of holography, each pixel of the hologram contributes to the overall reconstruction. There is no one-to-one correlation between a specific point (or image pixel) on the playback field and a specific optical modulation element (or hologram pixel). In other words, the modulated light emitted from the optical modulation layer is distributed across the entire playback field.

[0050] In these embodiments, the spatial position of the holographic reconstruction is determined by the refractive (focusing) capability of the Fourier transform lens. Figure 1 In the illustrated embodiment, the Fourier transform lens is a physical lens. That is, the Fourier transform lens is an optical Fourier transform lens, and the Fourier transform is performed optically. Any lens can act as a Fourier transform lens, but the lens's performance will limit the accuracy of the Fourier transform it performs. Those skilled in the art will understand how to use lenses to perform optical Fourier transforms.

[0051] Holographic computation

[0052] In some embodiments, the computer-generated hologram is a Fourier transform hologram, or simply a Fourier hologram or a Fourier-based hologram, wherein the image is reconstructed in the far field by utilizing the Fourier transform properties of a positive lens. The Fourier hologram is computed by Fourier transforming the desired light field in the reproduction plane back to the lens plane. The Fourier transform can be used to compute computer-generated Fourier holograms.

[0053] Fourier transform holograms can be computed using algorithms such as the Gerchberg-Saxton algorithm. Furthermore, the Gerchberg-Saxton algorithm can be used to compute holograms (i.e., Fourier transform holograms) in the Fourier domain from amplitude-only information (e.g., photographs) in the spatial domain. Phase information relevant to the object is efficiently “retrieved” from amplitude-only information in the spatial domain. In some embodiments, the Gerchberg-Saxton algorithm or variations thereof are used to compute computer-generated holograms from amplitude-only information.

[0054] The Gerchberg-Saxton algorithm takes into account the intensity cross section I of the beam in planes A and B, respectively. A (x, y) and I B (x, y) are known and I A (x, y) and I B (x, y) is related to a single Fourier transform. Using a given intensity cross section, approximate values ​​for the phase distributions ΨA(x, y) and ΨB(x, y) in planes A and B, respectively. The Gerchberg-Saxton algorithm finds a solution to the problem by following an iterative process. More specifically, the Gerchberg-Saxton algorithm iteratively applies spatial and spectral constraints while repeatedly passing the representation I between the spatial and Fourier (spectral or frequency) domains. A (x, y) and I B A dataset (x, y) containing amplitude and phase. A corresponding computer-generated hologram in the spectral domain is obtained through at least one iteration of the algorithm. The algorithm is convergent and arranged to produce a hologram representing the input image. The hologram can be an amplitude-only hologram, a phase-only hologram, or a fully complex hologram.

[0055] In some embodiments, an algorithm based on the Gerchberg-Saxton algorithm is used to compute a phase-only hologram, such as the algorithm described in British Patents 2,498,170 or 2,501,112, the entire contents of which are incorporated herein by reference. However, the embodiments disclosed herein describe the computation of a pure phase hologram only by way of example. In these embodiments, the Gerchberg-Saxton algorithm retrieves the phase information Ψ[u,v] of the Fourier transform of a dataset, which produces known amplitude information T[x,y], where the amplitude information T[x,y] represents the target image (e.g., a photograph). Since amplitude and phase are inherently combined in the Fourier transform, the amplitude and phase of the transform contain useful information about the accuracy of the computed dataset. Therefore, the algorithm can be used iteratively with feedback on both amplitude and phase information. However, in these embodiments, only the phase information Ψ[u,v] is used as the hologram to form a holographic representation of the target image at the image plane. The hologram is a dataset of phase values ​​(e.g., a 2D array).

[0056] In other embodiments, an algorithm based on the Gerchberg-Saxton algorithm is used to compute a fully complex hologram. A fully complex hologram is a hologram with amplitude and phase components. A hologram is a dataset (e.g., a 2D array) comprising an array of complex data values, where each complex data value includes an amplitude component and a phase component.

[0057] In some embodiments, the algorithm processes complex data, and the Fourier transform is a complex Fourier transform. Complex data can be considered to include (i) a real part and an imaginary part, or (ii) an amplitude component and a phase component. In some embodiments, the two components of the complex data are processed differently at different stages of the algorithm.

[0058] Figure 2A A first iteration of an algorithm for computing a pure phase hologram, according to some embodiments, is shown. The input to the algorithm is an input image 210, which comprises a 2D array of pixel or data values, where each pixel or data value is an amplitude or oscillation value. That is, each pixel or data value of the input image 210 does not have a phase component. Therefore, the input image 210 can be considered as a pure amplitude or pure oscillation or pure intensity distribution. An example of such an input image 210 is a photograph or a frame of a time-series video comprising frames. The first iteration of the algorithm begins with a data forming step 202A, which includes assigning random phase values ​​to each pixel of the input image using a random phase distribution (or random phase seed) 230 to form an initial complex dataset, wherein each data element of the set includes both amplitude and phase. In other words, the initial complex dataset represents the input image in the spatial domain.

[0059] First processing block 250 receives an initial complex dataset and performs a complex Fourier transform to form a complex dataset of Fourier transforms. Second processing block 253 receives the complex dataset of Fourier transforms and outputs a hologram 280A. In some embodiments, hologram 280A is a pure phase hologram. In these embodiments, second processing block 253 quantizes each phase value and sets each amplitude value to 1 to form hologram 280A. Each phase value is quantized according to the phase level that the pixels of the spatial light modulator used to "display" the pure phase hologram can represent. For example, if each pixel of the spatial light modulator provides 256 different phase levels, each phase value of the hologram is quantized to one of the 256 possible phase levels. Hologram 280A is a pure phase Fourier hologram representing an input image. In other embodiments, hologram 280A is a fully complex hologram comprising an array of complex data values ​​(each including an amplitude component and a phase component) derived from the received complex dataset of Fourier transforms. In some embodiments, the second processing block 253 constrains each complex data value to one of a plurality of allowed complex modulation levels to form a hologram 280A. The constraint step may include setting each complex data value to the nearest allowed complex modulation level in the complex plane. The hologram 280A can be said to represent an input image in the spectral domain, Fourier domain, or frequency domain. In some embodiments, the algorithm stops at this point.

[0060] However, in other embodiments, the algorithm continues, such as Figure 2A As shown by the dashed arrow in the image. In other words, Figure 2A The steps following the dashed arrow are optional (i.e., not required for all embodiments).

[0061] The third processing block 256 receives the modified complex dataset from the second processing block 253 and performs an inverse Fourier transform to form a complex dataset with an inverse Fourier transform. In other words, the complex dataset with the inverse Fourier transform represents the input image in the spatial domain.

[0062] The fourth processing block 259 receives the complex dataset of the inverse Fourier transform and extracts the amplitude value distribution 211A and the phase value distribution 213A. Optionally, the fourth processing block 259 evaluates the amplitude value distribution 211A. Specifically, the fourth processing block 259 can compare the amplitude value distribution 211A of the inverse Fourier transform complex dataset with the input image 210, which itself is, of course, the amplitude value distribution. If the difference between the amplitude value distribution 211A and the input image 210 is sufficiently small, the fourth processing block 259 can determine that the hologram 280A is acceptable. That is, if the difference between the amplitude value distribution 211A and the input image 210 is sufficiently small, the fourth processing block 259 can determine that the hologram 280A is a sufficiently accurate representation of the input image 210. In some embodiments, the phase value distribution 213A of the inverse Fourier transform complex dataset is ignored for comparison purposes. It will be understood that any number of different methods can be used to compare the amplitude value distribution 211A and the input image 210, and this disclosure is not limited to any particular method. In some embodiments, the mean squared error is calculated, and if the mean squared error is less than a threshold, the hologram 280A is considered acceptable. If the fourth processing block 259 determines that the hologram 280A is unacceptable, further iterations of the algorithm can be performed. However, this comparison step is not required, and in other embodiments, the number of algorithm iterations performed is predetermined, preset, or user-defined.

[0063] Figure 2B This represents the second iteration of the algorithm and any further iterations of the algorithm. The phase value distribution 213A from the previous iteration is fed back through the processing block of the algorithm. The amplitude value distribution 211A is rejected, while the amplitude value distribution of the input image 210 is accepted. In the first iteration, the data forming step 202A forms a first complex dataset by combining the amplitude value distribution of the input image 210 with the random phase distribution 230. However, in the second and subsequent iterations, the data forming step 202B includes forming a complex dataset by combining (i) the phase value distribution 213A from the previous iteration of the algorithm with (ii) the amplitude value distribution of the input image 210.

[0064] Then, with reference Figure 2A Processed in the same way as described Figure 2BThe complex dataset formed in step 202B is used to form the second iterative hologram 280B. The explanation of this process will not be repeated here. The algorithm can stop when the second iterative hologram 280B has been computed. However, any number of further iterations can be performed. It will be understood that the third processing block 256 is only needed if a fourth processing block 259 is required or further iterations are needed. The output hologram 280B typically improves with each iteration. However, in practice, a point is often reached where no more measurable improvement is observed, or the positive benefits of performing further iterations are outweighed by the negative effects of the additional processing time. Therefore, the algorithm is described as iterative and convergent.

[0065] Figure 2C This represents an alternative embodiment for the second and subsequent iterations. The phase value distribution 213A of the previous iteration is fed back through the processing block of the algorithm. The amplitude value distribution 211A is rejected, while an alternative amplitude value distribution is supported. In this alternative embodiment, the alternative amplitude value distribution is derived from the amplitude value distribution 211 of the previous iteration. Specifically, processing block 258 subtracts the amplitude value distribution 211 of the previous iteration from the amplitude value distribution of the input image 210, multiplies the difference by a gain factor α, and subtracts the scaled difference from the input image 210. This is mathematically represented by the following equation, where the subscript text and numbers represent the iteration number:

[0066]

[0067] in:

[0068] F′ is the inverse Fourier transform;

[0069] F is the forward Fourier transform;

[0070] R[x, y] is a complex dataset output by the third processing block 256;

[0071] T[x, y] is the input or target image;

[0072] It is the phase component;

[0073] Ψ is a phase hologram 280B;

[0074] It is a new amplitude value distribution 211B; and

[0075] α is the gain factor.

[0076] The gain factor α can be fixed or variable. In some embodiments, the gain factor α is determined based on the size and rate of the incoming target image data. In some embodiments, the gain factor α depends on the number of iterations. In some embodiments, the gain factor α is simply a function of the number of iterations.

[0077] Figure 2C The embodiments are in all other respects similar to Figure 2A and Figure 2B The implementation is the same. It can be said that a pure phase hologram Ψ(u,v) includes the phase distribution in the frequency domain or Fourier domain.

[0078] In some embodiments, a spatial light modulator is used to perform the Fourier transform. Specifically, holographic data is combined with second data providing optical power. That is, the data written into the spatial light modulator includes holographic data representing an object and lens data representing a lens. When displayed on the spatial light modulator and illuminated with light, the lens data simulates a physical lens—that is, it focuses light in the same way as a corresponding physical optics device. Therefore, the lens data provides optical or focused optical power. In these embodiments, [the following can be omitted] Figure 1 A physical Fourier transform lens 120 is used. Data representing the lens is known for computation. This data can be referred to as a software lens. For example, a pure phase lens can be formed by calculating the phase delay at each point of the lens due to variations in the lens's refractive index and the length of the optical path in spatial variations. For example, the optical path length at the center of a convex lens is greater than the optical path length at the lens's edge. A pure amplitude lens can be formed using Fresnel zone plates. In the field of computer-generated holography, it is also known how to combine data representing the lens with a hologram so that a Fourier transform of the hologram can be performed without a physical Fourier lens. In some embodiments, the lens data is combined with the hologram by simple addition (e.g., simple vector addition). In some embodiments, a physical lens is used in conjunction with a software lens to perform the Fourier transform. Alternatively, in other embodiments, the Fourier transform lens is omitted entirely, allowing holographic reconstruction to be performed in the far field. In a further embodiment, the hologram can be combined with grating data in the same manner—i.e., data arranged to perform grating functions such as image steering. Again, how to compute such data is known in this field. For example, a pure phase grating can be formed by simulating the phase delay caused by each point on the surface of a blazed grating. A pure amplitude grating can be simply superimposed on a pure amplitude hologram to provide angular steering for holographic reconstruction. The second data providing the lensing and / or steering can be referred to as an optical processing function or optical processing pattern, to distinguish it from the holographic data, which can be referred to as an image forming function or image forming pattern.

[0079] In some embodiments, the Fourier transform is performed jointly by a physical Fourier transform lens and a software lens. That is, some of the optical power contributing to the Fourier transform is provided by the software lens, while the remaining optical power contributing to the Fourier transform is provided by the physical optics.

[0080] In some embodiments, a real-time engine is provided, which is configured to receive image data and compute holograms in real time using the algorithm. In some embodiments, the image data is video comprising a sequence of image frames. In other embodiments, the holograms are pre-computed, stored in computer memory, and invoked as needed for display on an SLM. That is, in some embodiments, a repository of predetermined holograms is provided.

[0081] The embodiments illustrate Fourier holography and Gerchberg-Saxton type algorithms by way of example only. This disclosure is equally applicable to Fresnel holography and Fresnel holograms, which can be computed using similar methods. This disclosure also applies to holograms computed using other techniques, such as point cloud-based methods.

[0082] [Optical Modulation]

[0083] Spatial light modulators can be used to display diffraction patterns, including computer-generated holograms. If the hologram is a pure phase hologram, a spatial light modulator that modulates the phase is required. If the hologram is a fully complex hologram, a spatial light modulator that modulates both the phase and amplitude can be used, or a first spatial light modulator that modulates the phase and a second spatial light modulator that modulates the amplitude can be used.

[0084] In some embodiments, the light modulation element (i.e., pixel) of the spatial light modulator is a cell comprising liquid crystal. That is, in some embodiments, the spatial light modulator is a liquid crystal device wherein the optically active component is liquid crystal. Each liquid crystal cell is configured to selectively provide multiple light modulation levels. That is, each liquid crystal cell is configured at any given time to operate at one light modulation level selected from multiple possible light modulation levels. Each liquid crystal cell can be dynamically reconfigured to different light modulation levels from the multiple light modulation levels. In some embodiments, the spatial light modulator is a reflective liquid crystal on silicon (LCOS) spatial light modulator, but this disclosure is not limited to this type of spatial light modulator.

[0085] LCOS devices provide a dense array of light-modulating elements or pixels within a small aperture (e.g., a few centimeters wide). Pixels are typically about 10 micrometers or smaller, resulting in a diffraction angle of a few degrees, meaning the optical system can be compact. The small aperture of LCOS SLMs makes it easier to fully illuminate the light compared to other liquid crystal devices. LCOS devices are typically reflective, meaning the circuitry driving the LCOS SLM pixels can be buried beneath the reflective surface. This results in a higher aperture ratio. In other words, the pixels are closely packed, meaning there are virtually no dead zones between pixels. This is advantageous because it reduces optical noise in the replay field. LCOS SLMs use a silicon backplane, which has the advantage of making the pixels optically flat. This is particularly important for phase modulation devices.

[0086] The following examples are for reference only. Figure 3 A suitable LCOS SLM is described. The LCOS device is formed using a single-crystal silicon substrate 302. A two-dimensional square planar aluminum electrode array 301 is arranged on its upper surface, the electrodes being spaced apart by gaps 301a. Each electrode 301 can be addressed by a circuit 302a embedded in the substrate 302. Each electrode forms a corresponding planar mirror. An alignment layer 303 is disposed on the electrode array, and a liquid crystal layer 304 is disposed on the alignment layer 303. A second alignment layer 305 is disposed on a planar transparent layer 306 (e.g., glass). A single transparent electrode 307 (e.g., ITO) is disposed between the transparent layer 306 and the second alignment layer 305.

[0087] Each square electrode 301, together with the area covered by the transparent electrode 307 and the liquid crystal material in between, defines a controllable phase modulation element 308, commonly referred to as a pixel. The effective pixel area, or fill factor, is the percentage of the optically active portion of the total pixel, taking into account the gap 301a between pixels. By controlling the voltage applied to each electrode 301 relative to the transparent electrode 307, the properties of the liquid crystal material of the corresponding phase modulation element can be varied, thereby providing a variable delay for light incident upon it. The effect is that phase modulation is provided only for the wavefront, i.e., no amplitude effect occurs.

[0088] The described LCOS SLM outputs spatially modulated light in a reflective manner. The advantage of a reflective LCOS SLM is that the signal lines, gate lines, and transistors are located below the mirror surface, resulting in a high fill factor (typically greater than 90%) and high resolution. Another advantage of using a reflective LCOS spatial light modulator is that the liquid crystal layer can be half the thickness required when using a transmissive device. This significantly improves the switching speed of the liquid crystal (a key advantage for projecting moving video images). However, the teachings of this disclosure can also be applied to transmissive LCOS SLMs.

[0089] [Select color for each column]

[0090] Color selection in SLM typically means changing the assignment of values ​​to pixels for each incoming gray level. These assignments are often tailored to specific wavelengths and materials.

[0091] Typically, in an analog LCOS, there will be 3 separate gamma buffers, each corresponding to one of the RGB values. These are usually globally allocated (i.e., each pixel in the array at grayscale level GL24 will receive the same voltage from the currently selected gamma buffer (e.g., green).

[0092] Due to the global nature of these assignments, it is more difficult to subdivide the array into different colors.

[0093] Data is written to the array line by line. The value (e.g., voltage) at each pixel currently written to the line is latched from the column drivers at the array edges. These column drivers are connected to gamma buffers (via the MUX) and retrieve their values ​​from there. Gamma buffer selection (DEMUX) is typically done at the beginning of a frame via a color selection message in the high-speed video stream; sometimes, the message is sent at the beginning of each line. See also Figure 5 and Figure 6 .

[0094] In summary, this disclosure includes: instead of using messages in the video signal to select the gamma to be demultiplexed, pre-selecting the gamma for each column during device setup (e.g., via I2C messages) and keeping it fixed before reprogramming. Figure 4 Several different embodiments are shown in the figure.

[0095] Specifically, Figure 4 Some possible column assignments of this disclosure are shown, by way of example only. In embodiment A, each column corresponds to a different color. In embodiment B, color groups are shown. Embodiment C includes arbitrary arrangements of colors. Embodiment D includes all columns being a single color.

[0096] Figure 5 This illustrates an example of how pixels in data are mapped to pixels. The example shown includes a 10-channel MIPI. (As...) Figure 6 As shown, one approach is to demultiplex the gamma based on the pixel values ​​at the array. The multiplexed gamma is selected from one of three gamma buffers R, G, or B from the color message at the start of the frame.

[0097] In more detail, Figure 5This illustrates how a row of pixel values, consisting of ten pixel values, is received at a time. The first group of ten pixel values—pixels (00) to (09)—is received in parallel at the first moment. The second group of ten pixel values—pixels (10) to (19)—is received in parallel at the second moment immediately after the first moment, and so on. Thus, the first row of pixel values ​​in a pixel value array (e.g., representing an image or hologram) is received in groups of ten: pixels 1-10, then pixels 11-20, and so on. A pixel value array can comprise rows of thousands of pixel values. Each pixel value in a batch of ten pixel values ​​is assigned a pixel driver voltage according to a gamma calibration stored in a gamma buffer. A technician will be familiar with the concept of a gamma buffer and how to calibrate a pixelated liquid crystal device (e.g., for each wavelength, such as red, green, and blue) to convert pixel data values ​​(e.g., 6-bit binary numbers representing grayscale levels) into unit voltages. In the example, a single color gamma buffer is assigned to the pixel driver at the beginning of a video frame to indicate which single color gamma buffer should be consulted for the entire frame. This disclosure deviates from this practice and allows multiple datasets of different colored pixels to be delivered together and optionally assigned to different gamma buffers. This allows multiple patterns of different colored pixels to be displayed simultaneously on a pixel array of a display device. This approach works in conjunction with holography, where an image is reconstructed through diffraction, so each "image point" does not require red, green, and blue values. According to this disclosure, holographic pixels of different colors can be distributed on the array pixels according to any regular or irregular scheme. Pixels of different colors can be mixed together or arranged in repeating patterns. These methods are possible in holography and are generally not suitable for conventional displays.

[0098] Figure 7 It shows the following Figure 4 The color selection for each column in Implementation C. In some embodiments, COLOUR SELECT is an I2C or similar register that assigns values ​​to columns of the array, allowing for rapid selection of gamma buffers as video data is inserted into rows. In some embodiments, all gamma buffers are available simultaneously, and selection is made on the fly based on the assignment to each column.

[0099] Some embodiments include a register representing the color selection for each column of pixels, such as a 2-bit value representing which gamma to demultiplex. This allocation is performed during device setup (e.g., via I2C) and can be represented by a register.

[0100] When image data is assigned to pixels, a color selection value is checked before the gamma can be demultiplexed. This color selection value guides the pixel value to the correct gamma demultiplexing. This allows access to the associated gamma buffer during pixel writing of a row. See also Figure 7 .

[0101] Advantageously, this disclosure provides programmable color regions, each region having a unique gamma of that color tuned at the full bit depth (1:1 with the incoming video bit depth). For example... Figure 4 As shown, this disclosure further provides arbitrary and reassignable color regions. This disclosure also allows column-level color assignment without adding messages to the video stream.

[0102] Additional features

[0103] In some embodiments, when the improved spatial light modulator is included within an optical device including a light source, the light source is a laser such as a laser diode.

[0104] The methods and processes described herein may be embodied on a computer-readable medium. The term "computer-readable medium" includes media arranged for temporary or permanent storage of data, such as random access memory (RAM), read-only memory (ROM), buffer memory, flash memory, and cache memory. The term "computer-readable medium" should also be considered to include any medium or combination of media capable of storing machine-executable instructions, such that when executed by one or more processors, the instructions cause the machine to perform all or part of any or more of the methods described herein.

[0105] The term "computer-readable medium" also covers cloud-based storage systems. The term "computer-readable medium" includes, but is not limited to, one or more tangible and non-transitory data repositories (e.g., data volumes) in the form of solid-state memory chips, optical discs, disks, or any suitable combinations thereof. In some example embodiments, instructions for execution may be transmitted by a carrier medium. Examples of such carrier media include transient media (e.g., propagation signals for transmitting instructions).

[0106] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the appended claims. This disclosure covers all modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A pixel driver, the pixel driver being arranged to drive a display device to display a first color pixel pattern and a second color pixel pattern on a pixel array of the display device, wherein the pixel driver comprises: n data channels are arranged to receive n consecutive pixel values ​​of a row of pixel data. and A pixel voltage selector connects a first data channel of n data channels to a first color gamma buffer to retrieve a first voltage according to a first color calibration, and connects a second data channel of n data channels to a second color gamma buffer to retrieve a second voltage according to a second color calibration.

2. The pixel driver according to any one of the preceding claims, wherein, The pixel voltage selector also connects the third data channel of the n channels to the third color gamma buffer in order to retrieve the third voltage according to the third color calibration.

3. The pixel driver according to claim 2, wherein, The first color is red, the second color is blue, and the third color is green.

4. The pixel driver according to claim 2 or 3, wherein, The first data channel, the second data channel, and the third data channel are consecutive channels corresponding to consecutive pixel values ​​of the pixel data.

5. The pixel driver according to claim 2 or 3, wherein, The first data channel, the second data channel, and the third data channel are not consecutive data channels, and the pixel voltage selector connects the n data lines to gamma buffers of different colors in the following repeating order: first color, second color, third color, first color, second color, third color, first color, second color, third color.

6. The pixel driver according to claim 2 or 3, wherein, The first data channel, the second data channel, and the third data channel are not consecutive data channels, and the pixel voltage selector connects the n data channels to gamma buffers of different colors in the following repeating order: first color, first color, first color, second color, second color, second color, third color, third color, third color.

7. The pixel driver according to claim 2 or 3, wherein, The first data channel, the second data channel, and the third data channel are not consecutive data channels, and the pixel voltage selector connects the n data channels to gamma buffers of different colors in the following repeating order: third color, first color, first color, second color, first color, third color, second color, second color, third color.

8. The pixel driver according to claim 2 or 3, wherein, The first data channel, the second data channel, and the third data channel are not consecutive data channels, and the pixel voltage selector connects the n data channels to gamma buffers of different colors in the following repeating order: third color, third color, third color, third color, third color, third color, third color, third color, third color, third color.

9. The pixel driver according to any one of the preceding claims further includes a color selector arranged to dynamically determine the monochrome gamma buffer connected to each of the n data channels.

10. The pixel driver according to claim 9, wherein, The color selector includes an I2C OR register that allocates a monochrome gamma buffer to each data channel.

11. The pixel driver of claim 10, wherein, When pixel values ​​are received on the n data channels, the color selector assigns a monochrome gamma buffer to each data channel.

12. The pixel driver according to any one of the preceding claims, wherein, n is in the range of 6 to 20, for example, 8 to 12.

13. The pixel driver according to any one of the preceding claims, wherein, Each pixel value in the pixel data is a 6-bit binary number.

14. The pixel driver according to any one of the preceding claims, wherein, The display device is a phase modulator.

15. The pixel driver according to any one of the preceding claims, wherein, The display device is a silicon-based liquid crystal spatial light modulator.

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