Magnetic fluid based display for head mounted device

Abstract

The present invention is directed towards a compact, flexible and lightweight magnetic fluid-based display device that is capable of displaying better contrast under varying lightning conditions. The dual-layer display architecture combining a waveguide-based image projection system with an electromagnetically tunable ferrofluid-based light modulation panel enhances the realism and contrast of virtual imagery overlaid on real-world backgrounds, especially under high ambient light conditions, besides providing a substantially unobstructed field of view in which the user can directly observe his real physical surroundings under any environment conditions with better contrast sensitivity.

Description

FIELD OF THE INVENTIONEmbodiment of the present invention relates to magnetic fluidbased display device used in head mounted devices, and more particularlyto ferrofluid based displays that are capable of providing higher contrastand true black color in such head mounted devices.BACKGROUND OF THE INVENTIONWith widespread adoption of virtual / augmented reality (VR / AR)head mounted devices, high attention is being drawn towards reshapingoptical components, particularly display technology in such devices tomake them truly integral in everyday lives. While virtual reality devices canoffer completely immersive environment blocking the ambient light, see-through displays are desired in augmented reality devices for viewingenriched virtual content overlaid on the real world.Currently existing devices have made use of self-emitting lightemitting diodes (e.g. organic light emitting diodes [OLEDs]) foraugmented / virtual reality applications. However, they are accompaniedwith inherent disadvantage of high luminance requirement to obtainsharper image quality. Although this can be achieved by increasing theluminescent intensity, this brute force approach leads to a decrease in thelifetime of the materials and also higher energy consumption, whichincreasingly heats up the ar / vr devices.Displaying deep or truly black color in optical see through headmounted displays is a major challenge due to the inability to maintain highcontrast, particularly in bright outdoor environments. In natural sunlight orbright indoor lighting, the display often loses its color contrast, leading tovirtual images appearing washed out or difficult to distinguish from thereal-world surroundings. Thus, there is a need for refinement in the designof existing optical see-through head mounted displays to achieve bettercontrast ratios in common lighting conditions. Contrast ratio is typicallydetermined from person's ability to distinguish a visual stimulus based onthe differences in luminance between it and its environment. Visualstimulus that falls outside a person's contrast sensitivity function can bedealt with in two different manners, either by increasing the spatialfrequency (e.g., its size), or by increasing the contrast.However, in contemporary optical see-through devices, screenspace is valuable due to the limited field of view on most devices. Becauseof this, increasing spatial frequency in reduced contrast situations onlyworks so long as the image fits within the field of view of the device. Withthis upper bound on spatial frequency, any additional change to makeimagery distinguishable to the user must come from adjusting either thecontrast between the foreground and background color of the virtualimagery or the contrast between the foreground color of the virtualimagery with the user's physical environment.There are several factors that can cause a reduction in contrast withOST-HMDs, e.g., environmental factors like dynamic or saturated lightingconditions and see-through backgrounds. Tinted visors attached to see-through displays are often used as a practical solution to increase thecontrast between virtual imagery by reducing the illuminance levels of theenvironment lighting. However, the tinting inevitably reduces the visibilityof the real scenes in low lighting environments and prevents accuratecolor perception.Further, traditional optical see through- head mounted devices(OST-HMDs) rely on light modulation techniques like liquid crystal orOLED panels, but they struggle to achieve true black. OLED displays canprovide deep blacks, but in a transparent configuration, these displays stillcannot fully block light in certain conditions, making it difficult to generate aconsistent, true black background for virtual imagery. Furthermore,existing technologies may rely on multiple display layers, which can leadto bulky and less efficient designs. The need for a separate light sourceand complex components like diffusers and reflectors can increase thesize, power consumption, and cost of the display system.Many current systems suffer from reduced transparency whendisplaying virtual imagery. This limits the user's ability to interact with theirphysical environment while also viewing virtual content. There is often atrade-off between display performance (brightness, color, contrast) andtransparency, which is not ideal for an immersive, non-intrusive userexperience. In addition, these systems do not dynamically adjust tovarious levels of ambient light. For instance, in some cases, the display'slight intensity is either too high or too low, and the system does not adaptwell to fluctuating lighting conditions or varying user environments.Even more, some systems use energy-intensive methods toachieve acceptable image quality, including high-powered backlights orcomplex image-processing systems. This can result in short battery life inhead-mounted devices, a significant constraint for long-term use. Toaddress such limitations of limited contrast, color accuracy, inability otoachieve true black, bulky design panel, limited optical transparency, staticor non-adaptive light control, low efficiency and power consumption,researchers have faced immense challenge in presenting virtual content,specifically text information over OST-HMDs. They found that the legibilityon display is highly affected by the text drawing style, the see-thoughbackground, and interaction of various elements on the display scene.This indicates the need for further refinement in the design of optical see-through displays to achieve better contrast ratios in common lightingconditions.Thus, none of the above discussed configurations andcombinations of various display devices is capable of presenting anenergy-efficient OST HMD that can achieve true black, wide viewingangle, better response time, lower power consumption, higher contrastratio, wider color gamut, better image quality with acute sharpness, clarityand brightness, reduced chromatic aberration; still having light weight anda small form factor with enhanced flexibility.In order to the above issues, a thin and flexible see through displaydevice designed with a unique combination of constituting elements hasbeen attempted in present disclosure, and that may address one or moreof the challenges or needs mentioned herein, as well as provide otherbenefits and advantages. In the background of foregoing limitations, thereexists a need for light weight and high-performance display device that isnot posed with aforementioned challenges and offers ease of wearability,scalability and affordability in order to contribute to immersive experiencesof virtual world.The above information disclosed in this Background section is onlyfor enhancement of understanding of the background of the invention, andtherefore, it may contain information that does not form prior art.OBJECT OF THE INVENTIONAn object of the present invention is to provide a low-cost, high-performance, portable and light weight optical see through display devicethat provides higher contrast and better illumination while displaying bothreal and virtual worlds.Another object of the present invention is to provide a true, uniformdisplay of high resolution and contrast using ferrofluid based display inhead mounted device.Yet another object of the present invention is to provide an effectivedisplay technology providing high brightness, low power consumption,high color gamut, high contrast and high dynamic contrast.Yet another object of the present invention is to provide a ferro fluidbased display that makes up for a light and better contrast providingdevice capable of displaying true black color.Yet another object of the present invention is to provide light weightmagnetic fluid based display that provide enhanced contrast sensitivity inany kind of lightning environment ranging from dynamic or saturatedlighting conditions and see-through backgrounds.In yet another embodiment, easy to wear and comfortable magneticfluid based display that is capable of presenting virtual content in outdoorenvironments due to dynamic lightning conditions and uncontrollablebackgrounds.SUMMARYThis Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the Detailed Description.This Summary is not intended to identify key features or essential featuresof the claimed subject matter, nor is it intended to be used to limit thescope of the claimed subject matter. Furthermore, the claimed subjectmatter is not limited to implementations that solve any or all disadvantagesnoted in any part of this disclosure.In accordance with first aspect of the disclosure, a head mounted displaycharacterized in utilizing ferrofluid layer is disclosed. The systemcomprising of an image source; a first display panel comprising awaveguide that is optically coupled to the image source configured to emita display image. The system further comprising a second display panelcomprising a ferrofluid layer sandwiched between a front and reartransparent substrate; and a controller configured to receive the displayimage and generate a context-aware pixel-wise magnetic field across thesecond display panel, thereby aligning or dispersing the ferrofluid layer tomodulate transmission or blocking of ambient light through correspondingpixel regions. Significantly, here the second display panel is operative torender a true black appearance at pixel locations determined to be belowa brightness threshold in the display image.In accordance with second aspect of the disclosure, a method forrendering black in a head mounted display is disclosed, wherein themethod comprising steps of: receiving a display image from an imagesource; analysing and pre-processing, by a controller, the display image tonormalize and extract features therefrom; segmenting the display imageinto one or more regions for modulation-identifying high-contrast edges,uniform edges, and soft gradients for differentiated treatment; dynamicallyadjusting brightness threshold, by the controller based on a plurality ofparameters; comparing brightness value, by the controller, of thesegmented display image against the brightness threshold; generating acontext-aware pixel-wise magnetic field to modulate the segmenteddisplay image based on the compared brightness value; and rendering atrue black appearance, on a head mounted display, at pixel locationsdetermined to be below the brightness threshold in the display image.BRIEF DESCRIPTION OF THE DRAWINGSSo that the manner in which the above recited features of thepresent invention can be understood in detail, a more particular to thedescription of the invention, briefly summarized above, may be had byreference to embodiments, some of which are illustrated in the appendeddrawings. It is to be noted, however, that the appended drawings illustrateonly typical embodiments of this invention and are therefore not to beconsidered limiting of its scope, the invention may admit to other equallyeffective embodiments.These and other features, benefits and advantages of thepresent invention will become apparent by reference to the following textfigure, with like reference numbers referring to like structures across theviews, wherein:Fig. 1 illustrates OST-HMD, in accordance with an embodiment of thepresent invention.DETAILED DESCRIPTIONWhile the present invention is described herein by way of exampleusing embodiments and illustrative drawings, those skilled in the art willrecognize that the invention is not limited to the embodiments of drawingor drawings described and are not intended to represent the scale of thevarious components. Further, some components that may form a part ofthe invention may not be illustrated in certain figures, for ease ofillustration, and such omissions do not limit the embodiments outlined inany way. It should be understood that the drawings and detaileddescription thereto are not intended to limit the invention to the particularform disclosed, but on the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the scope of thepresent invention as defined by the appended claims. As used throughoutthis description, the word "may" be used in a permissive sense (i.e.,meaning having the potential to), rather than the mandatory sense, (i.e.,meaning must). Further, the words "a" or "an" mean "at least one" and theword "plurality" means "one or more" unless otherwise mentioned.Furthermore, the terminology and phraseology used herein is solely usedfor descriptive purposes and should not be construed as limiting in scope.Language such as "including," "comprising," "having," "containing," or"involving," and variations thereof, is intended to be broad and encompassthe subject matter listed thereafter, equivalents, and additional subjectmatter not recited, and is not intended to exclude other additives,components, integers or steps. Likewise, the term "comprising" isconsidered synonymous with the terms "including" or "containing" forapplicable legal purposes. Any discussion of documents, acts, materials,devices, articles, and the like are included in the specification solely for thepurpose of providing a context for the present invention. It is notsuggested or represented that any or all of these matters form part of theprior art base or were common general knowledge in the field relevant tothe present invention.Reference will now be made to embodiments, examples of whichare illustrated in the accompanying drawings. In the following description,numerous specific details are set forth in order to provide anunderstanding of the various described embodiments. However, it will beapparent to one of ordinary skill in the art that the various describedembodiments may be practiced without these specific details. In otherinstances, well-known methods, procedures, components, circuits, andnetworks have not been described in detail so as not to unnecessarilyobscure aspects of the embodiments. In this disclosure, whenever acomposition or an element or a group of elements is preceded with thetransitional phrase "comprising", it is understood that we also contemplatethe same composition, element or group of elements with transitionalphrases "consisting of", "consisting", "selected from the group of consistingof, "including", or "is" preceding the recitation of the composition, elementor group of elements and vice versa.The present invention is described hereinafter by variousembodiments with reference to the accompanying drawings, whereinreference numerals used in the accompanying drawing correspond to thelike elements throughout the description.This invention may, however, be embodied in many different formsand should not be construed as limited to the embodiment set forth herein.Rather, the embodiment is provided so that this disclosure will be thoroughand complete and will fully convey the scope of the invention to thoseskilled in the art. In the following detailed description, numeric values andranges are provided for various aspects of the implementations described.These values and ranges are to be treated as examples only and are notintended to limit the scope of the claims. In addition, a number of materialsare identified as suitable for various facets of the implementations. Thesematerials are to be treated as exemplary and are not intended to limit thescope of the invention.The present disclosure presents a see-through, mixed realitydisplay device that enables a user to observe digital information overlaidon the physical scenery. Referring to Fig. 1, in case of optical see-throughhead mounted device (OST-HMD) where the user is required to seethrough the real world, rendering truly dark / deep black color virtualinformation is a major challenge. Current optical see-through displayshave limited ability in display of color with low lightness such as black thathave low lightness in the hue, saturation, lightness (HSL) color space.These colours cannot be rendered by adding light into the scene. Thesecolours appear transparent on an OST-HMD, effectively not beingrendered at all.A known problem with this type of display method is that when theuser is in particularly bright environments, such as outdoors during theday, then the virtual imagery on the display tends to lose contrast inrelation to the environment. Thus, with known configurations there areerrors in display of virtual image as suboptimal black color is obtained incommon lightning conditions.To overcome above limitation, the present disclosure proposes anovel design and methodology for achieving true black and enhancedimage contrast in optical see-through head-mounted displays (OST-HMDs). The design of present disclosure incorporates an advanced multi-panel optical configuration with an integrated ferrofluid-based light-blocking system. A self-luminous micro-display paired with a waveguide-based optical system and a ferrofluid layer controlled via magnetic fieldsenables unprecedented contrast performance, particularly under highambient lighting conditions. Thus, the system of present disclosure,resolves existing limitations by using ferrofluid technology integrated with atransparent panel system and precision-controlled magnetic fields, asexplained in greater detail below.Referring now to Fig. 1, an OST-HMD display 1000 of presentdisclosure is illustrated that typically comprises of an image source 100and at least a first display panel and a second display panel that are atleast partly transparent, to provide a substantially unobstructed field ofview in which the user can directly observe his real physical surroundings.The image source 100 is configured to direct the illuminated light to form acolored display image. In one example embodiment, the image source 100may be a micro-OLED display that forms a colored display image or maybe a reflective liquid-crystal-on-silicon (LCOS) or digital micromirror display(DMD) device. The OST-HMD 1000 further comprises of a controller 500to provide suitable control signals that, when received by the image source100 causes the desired display image to be formed. The controller 500further manages image rendering and magnetic field generation forferrofluid pixel control, as will be explained later.In one ideal configuration, for purposes of forming compact OSTHMD 1000 and to avoid obstructing user's view of external imagery, theimage source 100 is shown offset from user's field of view. Since the microOLED panel 100 is self-luminous, a separate light source is not required,and the transmissive OST-HMD 1000 can be configured more simply andcompactly.Next, re-referring to Fig. 1, the OST-HMD 1000 comprises of atleast two panels that may be curved or planar (or portions thereof may beplanar). While these layers may be depicted rectangular, however theymay acquire other shapes based on shape of head mounted device orvisor. Broadly, in one significant embodiment the OST-HMD 1000comprises of a first layer 200 including a transparent waveguide 210 whichis positioned closer to user eye and configured to receive the displayimage and to shift the display image into the user's field of view.The waveguide 210 may be substantially transparent to externalimagery received normal to its front surface receiving the display image.Thus, the waveguide 210 may be positioned in front of the eye of theHMD-device user without obstructing the user's view of the externalimagery. Apropos, the light from the display image propagates through thewaveguide by reflection from the front and back surfaces of the waveguide210. In the illustrated embodiment, the direction of propagation is from thetemple side-i.e., the end portion of the waveguide closest to the user'sear-to the opposite end portion, which is oriented toward the bridge ofthe user's nose. The transparent waveguide 210 is responsible for imageredirection via Total Internal Reflection (TIR).In one exemplary embodiment, a collimator lens 150 may beprovided to collimate and reflect the light from the image source 100 intothe first of the series of transparent sections of the waveguide 210. Ideally,each ray of display light directed from the collimator 150 will encounterfront surface of the waveguide 210 above the Snell's Law critical angleand propagate through the transparent section by total internal reflection(TIR). Additionally, the waveguide 210 may be encompassing a beamsplitter or an out-coupling structure 250 to split the received ray into aplurality of parallel light rays distributed along the direction of propagationin the waveguide 210 and leave the back surface of the waveguide 210with an expanded exit pupil and evenly distributed image light.Thence, use of a micro-OLED image source 100 combined withtransparent waveguides 210 allows for a compact design withoutsacrificing transparency. The absence of a separate backlight sourcefurther reduces the bulk and energy requirements. The above waveguideconfiguration 210 is complemented with an additional panel that forms asecond layer 300 comprising of a transparent front 310 and rear substrate320 holding therebetween a layer of suspended particles 350, precisely offerrofluid that are capable of responding to applied magnetic field. The twotransparent glass substrates 310, 320 defines a space therebetween tohold the opaque ferrofluid 350 that responds to magnetic field that may beapplied using magnetic field generator having large field gradient. With therequisite of magnitude of applied magnetic field, as controlled by thecontroller 500, the ferrofluid droplets 350 may be directed to move toregions of display that requires to be displayed in absolute black.Notably, ferrofluid 350 is essentially a colloidal suspension whereinmagnetic particles (typically magnetite) of submicron size remainssuspended in a non-magnetic, transparent and immiscible carrier fluidsuch as water, hydrocarbons, fluorocarbons, esters, diesters and the liketo exhibit strong magnetic characteristics. A totally non-transparent blackliquid, the ferrofluid 350 typically comprising of magnetite particles coatedwith dispersing agent like oleic acid forms a spherical droplet that can bemoved or translated in response to applied magnetic field.In continuation to present disclosure, the two transparent glasssubstrates 310, 320 sandwiching the ferrofluid 350 in a stable state, areformed of conductive layer that generates a magnetic field in response toimage data of each pixel in order to orient the ferrofluid 350. In the abovetechnical arrangement, the magnetic particles in the ferrofluid 350 may beselected from ferrite, ferric oxide, nickel, molybdenum disulfide, andothers. The magnetic particles are as small as possible to be disperseduniformly and suspended constantly, preferably 0.001 to 10 micrometersin the diameter. In general, the particles remain randomly suspended,creating an opaque black layer due to strong light absorption andscattering and when the magnetic field is applied, the particles align alongthe magnetic field lines, forming transparent channels that allow light topass through between aligned particle chains.The distance in the space between the two transparent panels 310,320 may be equal to a row of at least some of the magnetic particles andmore preferably, is tens to hundreds times greater than the diameter of themagnetic particle (generally, several to hundreds micrometers) to ensurethe opaqueness of the ferrofluid 350 in the suspended state. In oneworking embodiment, the controller 500 of OST-HMD 1000 is configuredto selectively generate the magnetic field in response to an image controlsignal of each pixel of the ferrofluid 350. For example, the magnetic field isproduced by energizing a pattern electrode or solenoid coil for the pixelwith a given magnetizing current or directly by applicable magnetizingmeans.In the given arrangement, the ferrofluid 350 remains opaque withthe magnetic particles being uniformly suspended in the stable dispersedstate, when the magnetic field relative to a corresponding pixel is notgenerated by the controller 500 due to the attribute of an image controlsignal. As the result, the transmission of light is interrupted at the pixel bythe uniformly dispersed state of the magnetic particles in ferrofluid. Whenthe solenoid coil of the pixel is energized with a magnetizing current of thecontroller 500 in response to an image control signal, it produces themagnetic field. As the action of the magnetic field causes the magneticparticles in the ferrofluid 350 to align in straight rows, the light is notcompletely blocked by but passed between the rows of the magneticparticle in the pixel. Thence, based on image to be displayed before theuser eye, the controller 500 signals transmission or blocking of light by themagnetic particles suspended in the glass substrates forming the secondpanel 300.Thus, without a magnetic field, ferrofluid particles are randomlyoriented and dispersed, causing the layer to absorb or scatter incominglight, thus appearing black or opaque to the user. While, when themagnetic field is applied, particles form linear chains or rods along theapplied field direction. This structural transition reduces scattering andabsorption, making the layer more transparent and allowing light from theimage source 100 to reach the user's eye. As explained later, the degreeof alignment is tuned by the controller 500 using pulse width modulation toachieve optimal contrast and clarity to changing image content / outsidelightning conditions.In one exemplary embodiment, a method of achieving true blackcolor in an OST-HMD 1000 is explained. Accordingly, at first the state ofeach pixel of the display panel is obtained based on received image / videodata. Such a state may be a colored or a dark state that is obtained bycapturing brightness value of each pixel in the display panel according tothe input image data, which is an RGB image data. This brightness state ismeasured against the brightness threshold value and determining that thepixel is in a bright state when the brightness value of the pixel is greaterthan or equal to the threshold brightness; and under the condition that thebrightness value of the pixel is smaller than the threshold brightness,determining that the pixel is in a dark state.In one working embodiment, the solenoid coils or patternedelectrodes behind ferrofluid pixels are energized, and the generatedmagnetic field causes ferrofluid particles to align and block light. It shouldbe noted that the display regions and the image signal are in one-to-onecorrespondence, specifically, along a direction perpendicular to the displaypanel. This enables generating a controlled signal to fill the region ondisplay panel with adequate colours. In an event dark color is desired, theferrofluid 350 is activated to block the passage of light there through togenerate complete and true dark color.Briefly, the incoming image data (RGB values) from image source100 is analysed in real-time by a controller 500. Now, if the pixel'sbrightness is below threshold, it is categorized as a black pixel, and if thepixel's brightness is above threshold, it is categorized as a color pixel bythe controller 500. Each pixel's brightness level is evaluated against athreshold value to determine if it should appear as bright or dark (black).For the black pixels, the controller 500 disables the magnetic field atcorresponding pixels, leaving ferrofluid particles in a suspended,randomized state-thus blocking light. While, for bright pixels, thecontroller 500 activates the magnetic field, aligning the particles 350 andallowing light from the image source 100 to pass through clearly.In next working embodiment, the controller 500 utilizes artificialintelligence for controlling ferrofluids and dynamic context-aware lightmodulation in the display system by enabling real-time, adaptive, andintelligent management of the magnetic field applied to the ferrofluid. Atfirst, the controller 500 analyses the incoming image data and provideprecise control over each pixel's brightness level. In one workingembodiment, the controller 500 utilizes convolutional neural networks(CNNs) to process the image in real time to assess the pixel's brightnessand decide whether it needs to be bright or dark (black). The incomingimage data is analysed and segmented into regions (e.g. edges,gradients, textures, backgrounds) relevant for modulation-identifying high-contrast edges, uniform edges, and soft gradients for differentiatedtreatment. This ensures that the ferrofluid layer 350 is modulatedaccurately for high contrast and image clarity, reducing latency andimproving the quality of dynamic light modulation. In accordance with oneworking embodiment, the image features may be extracted such as edges(using any learned filters), texture, and local contrast.Next, in order to ensure optimal thresholding for determining whichpixels should be black or bright, the controller 500 employs likereinforcement learning or adaptive thresholding algorithms to dynamicallyadjust the brightness threshold based on various factors (ambient lighting,display conditions, user preferences, etc.). This will make the systemhighly adaptable to changing environmental conditions, improving theperformance of the display under diverse lighting situations. Thereinforcement learning (RL) based framework allows to iterativelyexperiments with different threshold values, instead of using fixedthreshold in response to changes in image content, environmentallightning or may be user feedback.For example, if the chosen threshold results in high-contrast,visually clear images, the controller 500 receives a positive reward and ismore likely to select similar thresholds in future. If the output is suboptimal,the controller 500 updates itself to explore alternative thresholds. Now, foreach pixel, the controller 500 instructs to generate a specific magnetic fieldstrength and pattern. If a pixel should be black, the magnetic field isdisabled or set so that ferrofluid nanoparticles remain in randomized,dispersed state, scattering or absorbing light and blocking transmission. Ifa pixel should be bright, the magnetic field is activated, the ferrofluidnanoparticles are activated and aligned into chains or structures along thefield lines, which become optically transparent and allow light to passthrough.The controller 500 thus adjusts light modulation based on context,such as the content being displayed (e.g., high contrast images vs.gradients) as the controller 500 can detect patterns and optimize themagnetic field to match the type of content being shown. For example, itcan apply stronger modulation or sharp edges and gentler modulation forgradients, ensuring the display adapts in real time to the visualrequirement of each scene. This enables more natural and visuallyappealing images, as the ferrofluid's response is tailored to the visualcontent being displayed.In one working embodiment, the controller 500 apply as sharper,binary magnetic filed control to ferrofluid particles 350, ensuring crispblack / bright transitions and maximizing contrasts. While for gradients orsoft transitions, the controller 500 utilizes pulse-width modulation (PWM) tocreate intermediate states in the ferrofluid, allowing partial lighttransmission and smooth visual gradients. Thus, the degree of alignmentand hence the opacity or transparency is finely tuned using PWM to varythe magnetic field strength. This enables not just binary (on / off) control,but also intermediate levels for smooth gradients or partial transparency.The controller 500, significantly, continuously monitors the display outputand environmental factors, for adjusting the magnetic field at each pixel inreal time. This ensures optimal contrast, clarity, and responsiveness tochanging image content or ambient lightning.Thus, the image generated by the micro-OLED 100 is projected intothe waveguide 210. A beam-splitting or out-coupling structure 250 (e.g.,diffractive gratings) redirects light toward the user's eye. Simultaneously,the ferrofluid layer 350 modulates which parts of this image are allowed topass through with high contrast and which parts are blocked to renderblack. The controller 500 thus pre-processes the received image andnormalize the brightness, denoise it and enhance the features forextraction. The image is segmented into regions of interest, which are thenclassified as either edges, gradient or background.This is followed by assigning adaptive thresholds per region,wherein each pixel is mapped to a magnetic field strength. For each pixel,the controller 500 set the magnetic filed to be applied accordingly, whilefor gradients, the field strength is interpolated for smooth transitions. Thus,by utilizing a ferrofluid-based panel that responds to an applied magneticfield, the proposed system can selectively block light in specific regions togenerate true black. The transparent substrates of the panel areconductive and insulated, and the ferrofluid 350 is sealed hermetically forstable performance over time. This feature allows for a more accurate andeffective representation of dark colors, especially in high-contrast scenes.The system's ability to manipulate the ferrofluid 350 to block light atspecific pixels helps to maintain high contrast and clarity even in brightsettings. The resulting imagery will retain its vibrancy, offering users amore engaging and visible experience in a range of lighting conditions.The magnetic field-based control of the ferrofluid allows for dynamicimage adjustment. The system can adapt in real time to the image data,improving both visual output and user experience, regardless ofenvironmental factors like ambient light. By utilizing the magneticmanipulation of the ferrofluid and the self-luminous micro-OLED panel, thetechnology reduces power consumption. The ability to dynamically adjustthe display image also means that unnecessary energy usage can beminimized. Eventually, the improved contrast and true black colorreproduction, combined with the transparent design of the system, ensurethat the user remains fully immersed in the virtual environment withoutlosing sight of the real world.In accordance with an embodiment, the head mounted devicecomprises a memory unit configured to store machine-readableinstructions. The machine-readable instructions may be loaded into thememory unit from a non-transitory machine-readable medium, such as, butnot limited to, CD-ROMs, DVD-ROMs and Flash Drives. Alternately, themachine-readable instructions may be loaded in a form of a computersoftware program into the memory unit. The memory unit in that mannermay be selected from a group comprising EPROM, EEPROM and Flashmemory. Further, a processor is operably connected with the memory unit.In various embodiments, the processor is one of, but not limited to, ageneral-purpose processor, an application specific integrated circuit(ASIC) and a field-programmable gate array (FPGA).In general, the word "module," as used herein, refers to logicembodied in hardware or firmware, or to a collection of softwareinstructions, written in a programming language, such as, for example,Java, C, or assembly. One or more software instructions in the modulesmay be embedded in firmware, such as an EPROM. It will be appreciatedthat modules may comprised connected logic units, such as gates and flip-flops, and may comprise programmable units, such as programmable gatearrays or processors. The modules described herein may be implementedas either software and / or hardware modules and may be stored in anytype of computer-readable medium or other computer storage device.Further, while one or more operations have been described asbeing performed by or otherwise related to certain modules, devices orentities, the operations may be performed by or otherwise related to anymodule, device or entity. As such, any function or operation that has beendescribed as being performed by a module could alternatively beperformed by a different server, by the cloud computing platform, or acombination thereof. It should be understood that the techniques of thepresent disclosure might be implemented using a variety of technologies.For example, the methods described herein may be implemented by aseries of computer executable instructions residing on a suitable computerreadable medium. Suitable computer readable media may include volatile(e.g., RAM) and / or non-volatile (e.g., ROM, disk) memory, carrier wavesand transmission media. Exemplary carrier waves may take the form ofelectrical, electromagnetic or optical signals conveying digital data steamsalong a local network or a publicly accessible network such as theInternet. It should also be understood that, unless specifically statedotherwise as apparent from the following discussion, it is appreciated thatthroughout the description, discussions utilizing terms such as "controlling"or "obtaining" or "computing" or "storing" or "receiving" or "determining" orthe like, refer to the action and processes of a computer system, or similarelectronic computing device, that processes and transforms datarepresented as physical (electronic) quantities within the computersystem's registers and memories into other data similarly represented asphysical quantities within the computer system memories or registers orother such information storage, transmission or display devices. Variousmodifications to these embodiments are apparent to those skilled in the artfrom the description and the accompanying drawings. The principlesassociated with the various embodiments described herein may be appliedto other embodiments. Therefore, the description is not intended to belimited to the embodiments shown along with the accompanying drawingsbut is to be providing broadest scope of consistent with the principles andthe novel and inventive features disclosed or suggested herein.Accordingly, the invention is anticipated to hold on to all other suchalternatives, modifications, and variations that fall within the scope of thepresent invention.

Claims

1. A head mounted display (1000), characterized in utilizing ferrofluid layer (350), comprising: an image source (100); a first display panel (200) comprising a waveguide (210) optically coupled to the image source (100) configured to emit a display image; a second display panel (300) comprising a ferrofluid layer (350) sandwiched between a front (310) and rear transparent substrate (320); and a controller (500) configured to receive the display image and generate a context-aware pixel-wise magnetic field across the second display panel (300), thereby aligning or dispersing the ferrofluid layer (350) to modulate transmission or blocking of ambient light through corresponding pixel regions; wherein the second display panel (300) is operative to render a true black appearance at pixel locations determined to be below a brightness threshold in the display image.

2. The head mounted display (1000), as claimed in claim 1, wherein the image source (100) is a micro-OLED display, a reflective liquid-crystal-on-silicon (LCOS) or a digital micromirror display device.

3. The head mounted display (1000), as claimed in claim 2, wherein the image source (100) is positioned offset from user's field of view.

4. The head mounted display (1000), as claimed in claim 1, further comprising a collimator (150) positioned between the image source (100) and the waveguide (210) to direct collimated light into the waveguide (210) at an angle above a Snell's Law critical angle for total internal reflection.

5. The head mounted display (1000), as claimed in claim 4, further comprising an out-coupling structure (250) disposed within the waveguide (210) to split the collimated light into multiple parallel rays along a direction of propagation toward a user's eye, thereby expanding the exit pupil of the display image.

6. The head mounted display (1000), as claimed in claim 1, wherein the ferrofluid layer (350) comprises magnetite (Fe3O4) particles coated with a dispersing agent selected from oleic acid, surfactants, or similar stabilizers, and suspended in a carrier fluid selected from hydrocarbons, esters, fluorocarbons, or water.

7. The head mounted display (1000), as claimed in claim 1, further comprising patterned electrodes or solenoid coils embedded within or adjacent to the front (310) and rear transparent substrate (320) for generating the magnetic field.

8. The head mounted display (1000), as claimed in claim 1, wherein the controller (500) is further configured to compute a brightness value for each pixel of the input image, compare the brightness to the brightness threshold, and activate the ferrofluid layer (350) to block light in regions below the brightness threshold to create a dark appearance.

9. The head mounted display (1000), as claimed in claim 1, wherein the controller (500) is further configured to tune degree of alignment of the ferrofluid layer (350) using pulse width modulation to achieve optimal contrast and clarity.

10. The head mounted display (1000), as claimed in claim 1, wherein the controller (500) is configured to determine that the pixel is in a bright state in an event brightness value of the pixel is greater than or equal to the brightness threshold, and the pixel is in a dark state in an event the brightness value of the pixel if lower than the brightness threshold.

11. The head mounted display (1000), as claimed in claim 10, wherein the controller (500) is configured to generate the context-aware pixel-wise magnetic field across the second display panel (300) in steps of: analysing and pre-processing the display image to normalize and extract features; segmenting the display image into one or more regions for modulation-identifying high-contrast edges, uniform edges, and soft gradients for differentiated treatment; dynamically adjusting the brightness threshold based on a plurality of parameters; and generating the context-aware pixel-wise magnetic field to modulate the segmented display image using the dynamically adjusted brightness threshold.

12. The head mounted display (1000), as claimed in 11, wherein the brightness threshold is adjusted based on the plurality of parameters consisting image content, environmental lightning or user feedback or a combination thereof.

13. The head mounted display (1000), as claimed in claim 11, wherein the controller (500) is configured to utilize convolutional neural networks (CNNs) to process the display image in real time to assess the pixel's brightness values.

14. The head mounted display (1000), as claimed in claim 11, wherein the brightness threshold is dynamically adjusted using reinforcement learning or adaptive thresholding algorithms.

15. A method for rendering black in a head mounted display (1000), comprising steps of: receiving a display image from an image source (100); analysing and pre-processing, by a controller (500), the display image to normalize and extract features therefrom; segmenting the display image into one or more regions, by the controller (500) for modulation-identifying high-contrast edges, uniform edges, and soft gradients for differentiated treatment; dynamically adjusting brightness threshold, by the controller (500) based on a plurality of parameters; comparing brightness value, by the controller (500), of the segmented display image against the brightness threshold; generating a context-aware pixel-wise magnetic field to modulate the segmented display image based on the compared brightness value; and rendering a true black appearance, on a head mounted display (1000), at pixel locations determined to be below the brightness threshold in the display image.

16. The method, as claimed in claim 15, wherein the brightness threshold is adjusted based on the plurality of parameters consisting image content, environmental lightning or user feedback or a combination thereof.

17. The method, as claimed in claim 15, further comprising utilizing convolutional neural networks (CNNs) to process the display image in real time to assess the pixel's brightness values.

18. The method, as claimed in claim 15, wherein the brightness threshold is dynamically adjusted using reinforcement learning or adaptive thresholding algorithms.

19. The method, as claimed in claim 15, wherein the context-aware magnetic field to modulate the segmented display image by way of tuning degree of alignment of a ferrofluid layer (350) of the head mounted display (1000) using pulse width modulation.

20. The method, as claimed in claim 15, wherein a pixel of the display image is in a bright state in an event brightness value of the pixel is greater than or equal to the brightness threshold, and the pixel is in a dark state in an event the brightness value of the pixel if lower than the brightness threshold.