CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/251,503, filed October 1, 2021, entitled “REFLECTIVE DISPLAY APPARATUS WITH OPTICALLY ABSORPTIVE FLUID,” the entirety of which is incorporated by reference herein.

TECHNICAL FIELD

[0002] This disclosure relates to display devices, and in particular to reflective fluidic display devices.

BACKGROUND

[0003] Some reflective display devices can include fluids that can be controllably positioned between a reflective surface and a viewer to display an observed reflector state or a covered reflector state. One example of such a reflective display device includes an optical cavity defined in part by an optically transparent window positioned between a reflective surface and an transparent mechanically flexible front surface. The optical cavity is coupled with a reservoir via a conduit, where the reservoir, the optical cavity, and the conduit are filled with the fluid. During operation, the fluid is selectively moved in and out of the optical cavity to cause covered reflector and observed reflector states.

SUMMARY

[0004] In some aspects, the techniques described herein relate to a display apparatus, including: a variable volume optical chamber including an optically transparent window and a moveable reflective surface positioned opposite the optically transparent window, the moveable reflective surface being normally forced to push against the optically transparent window; a variable volume fluid reservoir defined by at least one deformable membrane; a conduit providing fluid communication between the optical chamber and the fluid reservoir; and an optically absorptive fluid moveable between the variable volume optical chamber and the variable volume fluid reservoir via the conduit, wherein the at least one deformable membrane is configured to deform responsive to an actuation force and reduce a volume of the variable volume fluid reservoir causing the fluid to move from the variable volume fluid reservoir to the variable volume optical chamber via the conduit, push the moveable reflective surface away from the optically transparent window, and occupy a volume between the moveable reflective surface and the optically transparent window.

[0005] In some aspects, the techniques described herein relate to a display apparatus, wherein a magnitude of the actuation force is greater than a magnitude of a force normally forcing the moveable reflective surface to push against the transparent window. In some aspects, the techniques described herein relate to a display apparatus, wherein responsive to removal of the actuation force, the moveable reflective surface moves towards the optically transparent window and displaces the fluid between the moveable reflective surface and the optically transparent window into the variable volume fluid reservoir causing the at least one deformable membrane to deform and increase the volume of the variable volume fluid reservoir to accommodate the fluid pushed out of the variable volume optical chamber.

[0006] In some aspects, the techniques described herein relate to a display apparatus, wherein removal of the actuation force includes reduction in the magnitude of the actuation force to a value that is less than the magnitude of the force normally forcing the moveable reflective surface to push against the transparent window. In some aspects, the techniques described herein relate to a display apparatus, wherein the actuation force is a mechanical force external to the variable volume fluid reservoir. In some aspects, the techniques described herein relate to a display apparatus, wherein the optically transparent window is rigid. In some aspects, the techniques described herein relate to a display apparatus, wherein the combination of the variable volume optical chamber, the variable volume fluid reservoir and the conduit form a sealed chamber enclosing the fluid at a pressure that is greater than an atmospheric pressure [0007] In some aspects, the techniques described herein relate to a display apparatus, wherein the conduit is a valve-less conduit. In some aspects, the techniques described herein relate to a display apparatus, wherein the moveable reflective surface is positioned on a piston that is pushed towards the optically transparent window by a spring mechanism. In some aspects, the techniques described herein relate to a display apparatus, wherein the moveable reflective surface is mounted on a spring mechanism extending between a periphery of the moveable reflective surface and an inner surface of the variable volume optical chamber.

[0008] In some aspects, the techniques described herein relate to a display apparatus, wherein a rigid optically transparent membrane is positioned between the movable reflective surface and the optically transparent window, the rigid optically transparent membrane mounted on a hinge extending between the rigid optically transparent membrane and an internal surface of the display apparatus, the hinge allowing the rigid optically transparent membrane to move responsive to the movement of the moveable reflective surface. In some aspects, the techniques described herein relate to a display apparatus, wherein the rigid optically transparent membrane includes a thermoplastic material. In some aspects, the techniques described herein relate to a display apparatus, wherein a flexible optically transparent membrane is positioned between the moveable reflective surface and the optically transparent window. In some aspects, the techniques described herein relate to a display apparatus, wherein the at least one deformable membrane includes an elastomer material.

[0009] In some aspects, the techniques described herein relate to a display apparatus, wherein the at least one deformable membrane includes a first sealable port and the second sealable port, wherein the opaque fluid is filled into the fluid reservoir via the first sealable port while simultaneously drawing air out of the variable volume fluid reservoir via the second sealable port. In some aspects, the techniques described herein relate to a display apparatus, further including at least one light source positioned along a periphery of the optically transparent window such that light emitted by the light source is totally internally reflected by a front surface of the optically transparent window and is directed towards the moveable reflective surface. In some aspects, the techniques described herein relate to a display apparatus, further including an ultraviolet filter disposed over the optically transparent window.

[0010] In some aspects, the techniques described herein relate to a display apparatus, wherein the optically absorptive fluid includes at least one of ultraviolet stabilizers or antioxidants, such as octylmethoxycinnamate, avobenzone, hydroxybenzoates, benzotriazoles, hydroxyphenyltrazines, oxanilides, or antioxidants and free radical scavengers from the phenolic, thioester, phosphite, aminic chemical classes, or blends thereof. In some aspects, the techniques described herein relate to a display apparatus, wherein the optically absorptive fluid includes at least one organic or inorganic pigment, such as quinacridone, metal phthalocyanine, or carbon black pigment or at least one phthalocyanine, acid, basic, azoic, nitro, vat, mordant, sulfur or other synthetic dye. In some aspects, the techniques described herein relate to a display apparatus including a flexible optically transparent membrane positioned between the moveable reflective surface and the optically transparent window, a stiffener coupled with at least a portion of the flexible optically transparent membrane, and a spring mechanism providing a force to the stiffener to push against the optically transparent window, where the moveable reflective surface is positioned on a surface of the stiffener facing the optically transparent window.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. [0012] Figure 1 illustrates a cross-sectional view of a display element.

[0013] Figure 2 shows a portion of a cross-section of an example display element where springs are positioned along a periphery of the piston.

[0014] Figure 3 shows a portion of the cross-sectional view of the display element including a hinged optically transparent membrane.

[0015] Figure 4 shows an exploded view of a portion of an example display module.

[0016] Figure 5 shows an exploded view of an example actuator assembly that can be used in conjunction with the display elements discussed herein.

[0017] Figure 6 shows an exploded view of a color display module.

[0018] Figure 7 shows a portion of a cross-sectional view of an example display module with edge lighting.

[0019] Figure 8 shows an exploded view of an example display module including edge lighting.

[0020] Figure 9 shows a cross-sectional view of a portion of a display module including a hinged optically transparent membrane.

[0021] Figure 10 shows a cross-sectional view of an example color display element.

[0022] Figures 11A and 11B show cross-sectional views of another example display module including a stiffener coupled with an optically transparent membrane.

[0023] Additional advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the disclosure. The advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.

[0024] Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0025] Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0026] Figure 1 illustrates a cross-sectional view of a display element 100. In particular, the display element 100 can be utilized as a pixel or a sub-pixel of a reflective display device. The display element 100 includes a variable volume optical chamber 102, a variable volume fluid reservoir 104, and a conduit 106 providing fluid communication between the optical chamber 102 and the fluid reservoir 104. The variable volume optical chamber 102 the variable volume fluid reservoir 104, and the conduit 106 can enclose an optically absorptive fluid 108. The variable volume optical chamber 102 can be include an optically transparent window 110, sidewalls 112, and an optically transparent membrane 114. A moveable reflective surface 116 is positioned on the side of the optically transparent membrane 114 that is facing away from the optically transparent window 110.

[0027] The optically absorptive fluid 108 is selectively confined in the space formed by the optically transparent window 110, the sidewalls 112, and the optically transparent membrane 114. The moveable reflective surface 116 can be configured to move towards or away from the optically transparent window 110. In particular, the moveable reflective surface 116 can be normally forced to push against the optically transparent window 110. The optically transparent membrane 114 can be a rigid membrane and can be coupled to the inner surfaces of the variable volume optical chamber 102 by one or more hinged mechanisms that allow the optically transparent membrane 114 to move towards or away from the optically transparent window 110. For example, when the moveable reflective surface 116 moves towards the optically transparent window 110, the moveable reflective surface 116 can push the optically transparent membrane 114 also towards the optically transparent window 110.

[0028] The variable volume fluid reservoir 104 includes at least one rigid sidewall 118 and at least one deformable membrane 120. The at least one deformable membrane 120 can be anon- porous elastomeric material that can deform responsive to a deforming force from an actuator. As an example, the at least one deformable membrane 120 can include one or more actuator receiving areas 162 that interface with one or more actuators. In particular, the at least one deformable membrane 120 can deform in a manner that reduces a volume of the variable volume fluid reservoir 104 and displaces the optically absorptive fluid 108 from the variable volume fluid reservoir 104 to the variable volume optical chamber 102. When the deforming force is removed, the at least one deformable membrane 120 can regain its original shape by the displacement of the optically absorptive fluid 108 from the variable volume optical chamber 102 into the variable volume fluid reservoir 104, thereby restoring the volume of the variable volume fluid reservoir 104. The shape of the at least one deformable membrane 120 (and therefore the volume of the variable volume fluid reservoir 104), after the removal of the deforming force can depend upon the difference between the pressure of the optically absorptive fluid 108 within the variable volume fluid reservoir 104 and the atmospheric pressure on the other side of the at least one deformable membrane 120.

[0029] The moveable reflective surface 116 can be a surface of a piston 122, which is attached to a connecting rod 124. The surface of the piston 122 can be finished to behave as a Lambertian reflector. In some examples, the reflective surface 116 can include a coating over the surface of the piston 122 that faces the optically transparent window 110, where the coating can be a Lambertian reflector or a retroreflector. The piston 122 can be contained within a cylinder 126 formed within the body of the display element 100. The connecting rod 124 can be contained in part within a connecting rod conduit 128. A spring mechanism 130 can be positioned between the piston and the body of the display element 100. The spring mechanism 130 is configured to provide a normal force to the piston 122 and in turn to the moveable reflective surface 116 to push against the optically transparent window 110.

[0030] During operation, the display element 100 can be in one of three states: an observed reflector state, a covered reflector state, and an intermediate state between the two. In the observed reflector state, the moveable reflective surface 116 rests against the optically transparent window 110 without the presence of the optically absorptive fluid 108 between the optically transparent window 110 and the moveable reflective surface 116. As there is no optically absorptive fluid 108 between the optically transparent window 110 and the moveable reflective surface 116, a viewer would observe the light reflected from the moveable reflective surface 116. In the observed reflector state, the actuator does not impose a deforming force on the at least one deformable membrane 120. Or even if an actuation force is present, the magnitude of the actuation force is less than the force with which the spring mechanism 130 pushes the moveable reflective surface 116 towards the optically transparent window 110. This causes the optically absorptive fluid 108 in the variable volume optical chamber 102 to be pushed out of the variable volume optical chamber 102 and into the variable volume fluid reservoir 104 via the conduit 106. The at least one deformable membrane 120 deforms to accommodate the optically absorptive fluid 108 pushed out of the variable volume optical chamber 102 and into the variable volume fluid reservoir 104. In some instances, in the observed reflector state, while it is desired that no optically absorptive fluid 108 be present between the optically transparent window 110 and the moveable reflective surface 116, in practice it may be difficult to completely remove all of the optically absorptive fluid 108 and trace amounts of optically absorptive fluid 108 may be present. As long as the trace amounts of optically absorptive fluid 108 do not reduce the apparent reflectivity of the moveable reflective surface 116 to an observer from the other side of the optically transparent window 110 by more than 10 % of that when there is no optically absorptive fluid 108 present, the display element 100 can still be considered as being in the observed reflector state.

[0031] To move from the observed reflector state to a covered reflector state, the actuator is activated to impose a force on the at least one deformable membrane 120. The magnitude of the actuation force is greater than the force normally forcing the moveable reflective surface 116 to push against the optically transparent window 110. In particular, the magnitude of the actuation force can be greater than the force imposed by the spring mechanism 130 on the piston 122. The actuation force causes the at least one deformable membrane 120 to deform and thereby reduce the volume of the variable volume fluid reservoir 104. As a result, at least a portion of the optically absorptive fluid 108 is displaced out of the variable volume fluid reservoir 104 and into the variable volume optical chamber 102 via the conduit 106. The optically absorptive fluid 108 pushes the piston 122 away from the optically transparent window 110 and occupies the volume between the moveable reflective surface 116 and the optically transparent window 110. Unlike in the observed reflector state, where light incident on the display element 100 was reflected by the moveable reflective surface 116, in the covered reflector state, the light incident on the display element 100 does not reach the moveable reflective surface 116 and is instead partially absorbed by the optically absorptive fluid 108 with the remainder reflected to the viewer. The intermediate state between the observed reflector state and the covered reflector state creates an intermediate amount of optical absorption in the display element between the extreme cases by partially covering the reflector with optically absorptive fluid 108. In the intermediate state, some of the incident light may reach the moveable reflective surface 116 and be reflected back through the optically transparent window 110. However, the magnitude of the light reflected is less than that in the observed reflector state and greater than that in the covered reflector state.

[0032] As long as the actuation force is maintained at the at least one deformable membrane 120, the force by the spring mechanism 130 on the piston 122 cannot push away the optically absorptive fluid 108 present between the moveable reflective surface 116 and the optically transparent window 110. Thus, the actuation force on the at least one deformable membrane 120 counteracts the force of the spring mechanism 130 to maintain the piston 122 in a retracted position. When the actuation force is removed, the force counteracting the force of the spring mechanism 130 on the piston 122 is removed. Therefore, the spring mechanism 130 can extend the piston 122 towards the optically transparent window 110 and push the optically absorptive fluid 108 out of the variable volume optical chamber 102 and into the variable volume fluid reservoir 104.

[0033] The combination of the variable volume optical chamber 102, the variable volume fluid reservoir 104, and the conduit 106 form a sealed chamber enclosing the optically absorptive fluid 108 at a pressure that is greater than an atmospheric pressure outside of the display element 100. This is in contrast with some traditional display elements that maintain the optically absorptive fluid at a negative pressure with respect to the atmospheric pressure. Maintaining the optically absorptive fluid at a negative pressure can increase the risk of air ingress into the otherwise sealed chamber via punctures or cracks in the membranes or sidewalls of the traditional display element, or through diffusion mechanisms in compromised materials. Air ingress into the display element result in variability in the internal volume, which now consists of a substantially non-compressible liquid in the form of the optically absorptive fluid and a compressible fluid in the form of air. The presence of the compressible air can reduce the effectiveness with which the actuation force acting on the at least one deformable membrane can push the piston away from the optically transparent window. This may result in the display element remaining in the observed reflector state or the intermediate state despite the presence of the actuation force that absent the compressible air would otherwise be sufficient to position the display element in the covered reflector state. To mitigate this drawback, the actuator may have to be repeatedly recalibrated or replaced — affecting the reliability of the display element. Moreover, if the air present in the display element migrates into the variable volume optical chamber during the covered reflector state, the air may displace the optically absorptive fluid at one or more locations between the optically transparent window and the moveable reflective surface, resulting in at least some portion of the display element reflecting light in a covered reflector state. This can degrade the contrast of the display element or reduce the color gamut of the display device in which the display element is integrated. These drawbacks related to the negative pressure display elements are avoided in the display elements discussed herein, where the optically absorptive fluid is maintained at a positive pressure in relation to the atmospheric pressure to ensure there is no fundamental driving force for air ingress.

[0034] The optically transparent window 110 can form the outermost surface of the display element 100 that faces the viewer. In some traditional reflective fluidic display elements, a soft and flexible membrane such as a stretched elastomer is utilized as the front facing surface. The optical chamber of such display elements has a constant volume and is further defined by a rigid transparent window positioned over a reflective surface. The rigid transparent window separates the reflective surface from the optically absorptive fluid within the optical chamber. The front facing soft and flexible membrane can be vulnerable to impact from environmental factors. In some instances, to mitigate the risk from impact, an additional rigid transparent surface is added in front of the membrane. However, the additional rigid transparent surface can increase Fresnel reflective losses and reduce the optical performance of the display element. To mitigate these drawbacks, the display element 100 employs a rigid optically transparent window 110 is the outermost surface. The rigidity of the optically transparent window 110 can protect the display element 100 against environmental impacts. Further, the rigid optically transparent window 110 lends itself to relatively easy manufacturing as compared to that of the soft and flexible membrane.

[0035] The conduit 106 can have a cross-section area that is smaller than the cross-section area of the both the variable volume optical chamber 102 and the variable volume fluid reservoir 104. In some instances, the display element 100 can include more than one conduit to increase the flow rate of the optically absorptive fluid 108 between the variable volume optical chamber 102 and the variable volume fluid reservoir 104. For example, the display element 100 can include a conduit positioned on the opposite side of the conduit 106 and connects the variable volume optical chamber 102 with the variable volume fluid reservoir 104. The conduit 106 may also be devoid of any valves that control the flow rate of the optically absorptive fluid 108.

[0036] The spring mechanism 130 includes a spring 134 that is positioned around the connecting rod 124 and between an inner surface 132 of the piston 122 and an inner surface 136 of the cylinder 126. The spring 134 can provide a constant force that normally pushes the piston 122 towards the optically transparent window 110. The connecting rod 124 reciprocates within the connecting rod conduit 128 to reduce any lateral movement of the piston 122. In some examples, the sidewalls of the cylinder and the piston 122 can include slots and tracks that not only reduce the risk of lateral or tilting movement, but also reduce the risk of rotational movement of the piston 122. The interface between the slots and the tracks can be lubricated to reduce the friction between the slots and the tracks, thereby reducing the risk of the piston 122 being undesirably stuck within the cylinder 126 or increase the magnitude of force from the actuator needed to move the piston 122.

[0037] The spring mechanism 130 shown in Figure 1 is only an example. Other mechanisms that apply a constant force to the piston 122 could also be used. For example, Figure 2 shows a portion of a cross-section of an example display element 200 where springs are positioned along a periphery of the piston 122. Specifically, a first peripheral spring 202 and a second peripheral spring 204 can be positioned near the periphery 206 or the edge of the piston 122. The first peripheral spring 202 and the second peripheral spring 204 can extend between the inner surface 136 of the display element 100 and the piston 122. In some examples, more than two peripheral springs can be included along the periphery 206 of the piston 122. Other types of springs such as, for example, torsional springs, leaf springs, polymer springs, elastomer springs, Bellville washers, flat springs, etc. can be utilized in place of or in addition to the spring 134 or the first peripheral spring 202 and the second peripheral spring 204. In some instances, magnets can be positioned on the inner surface 136 of the display element 100 and the piston 122 to provide the force to push the piston 122 towards the optically transparent window 110. In some approaches, positioning the springs along the periphery 206 of the piston 122 can eliminate the need for the connecting rod 124, thereby reducing the size of the display element 200. In some other approaches, a combination of the spring mechanism 130 shown in Figure 1, and that shown in Figure 2 can be employed.

[0038] The optically transparent membrane 114 can separate the piston 122 from the variable volume optical chamber 102. In some approaches, the display element 100 can be devoid of the optically transparent membrane 114, and the moveable reflective surface 116 of the piston 122 can instead make direct contact with the optically absorptive fluid 108. In such instances, the periphery 206 of the piston 122 can include one or more seals such as, for example, sealing rings, to prevent the optically absorptive fluid 108 from escaping into the cylinder 126. In instances where the optically transparent membrane 114 is utilized, a hinge mechanism can be utilized to allow the optically transparent membrane 114 to not only seal the optically absorptive fluid 108 from the cylinder 126 but also allow the optically transparent membrane 114 to move with the piston 122. Figure 3 shows a portion of the cross-sectional view of the display element 100 including a hinged optically transparent membrane 114. In particular, Figure 3 shows a hinge 138 extending between the optically transparent membrane 114 and an internal surface such as a sidewall 142 of the display element 100. The hinge 138 can be a living hinge formed of the same material as the optically transparent membrane 114. In some instances, the hinge 138 can be a rubber or plastic material that is adhered to the optically transparent membrane 114 and the sidewall 142. In some instance, the hinge 138 can be a rolling hinge. The hinge 138 can extend around the periphery of the optically transparent membrane 114. In some instances, the hinge 138 can be continuous. In some other instances, the hinge 138 can be discontinuous. For example, the hinge 138 can include apertures to allow the conduit 106 to pass through between the variable volume optical chamber 102 and the variable volume fluid reservoir 104. [0039] In some examples, the optically transparent membrane 114 can be flexible. Having a flexible membrane can allow ease of movement of the optically transparent membrane 114 in conjunction with the reciprocating movement of the piston 122. However, in some instances, while the flexible membrane provides ease of movement of the membrane, the flexible membrane may increase the risk of the optically absorptive fluid 108 being trapped between the optically transparent membrane 114 and the optically transparent window 110 when the moveable reflective surface 116 is pushed against the optically transparent window 110. Because of the flexibility of the membrane, the membrane can deform when pressed between the piston 122 and the optically transparent window 110. This deformation can result in formation of pockets between the optically transparent membrane 114 and the optically transparent window 110, which pockets can get filled with the optically absorptive fluid 108. The presence of the optically absorptive fluid 108 in the observed reflector state can degrade the optical performance of the display element 100. A rigid optically transparent membrane 114 on the other hand would not deform when pressed between the optically transparent window 110 and the piston 122, thereby reducing the risk of formation of pockets of optically absorptive fluid 108 between the optically transparent window 110 and the optically transparent membrane 114. While the rigidity of the optically transparent membrane 114 may increase the resistance to the movement of the piston 122, the hinge mechanism such as, for example, that shown in Figure 3 can mitigate the risk of undue resistance to the movement of the piston 122. Thus, the combination of the rigid optically transparent membrane 114 and the hinge mechanism can not only allow the optically transparent membrane 114 to move with ease in conjunction with the piston 122 but also reduce the risk of degradation of optical performance of the display element 100 due to formation of pockets of optically absorptive fluid 108 between the optically transparent membrane 114 and the optically transparent window 110. In some instances, the rigid optically transparent membrane 114 can be formed using optically transparent polymers such as, for example, polyester which can be hydroformed, thermoformed, or vacuum-formed to create the hinged mechanism positioned between the optically transparent membrane 114 and the surfaces of the display element 100.

[0040] Figure 4 shows an exploded view of a portion of an example display module 400. In particular, Figure 4 shows a 2x2 display module 400 that includes four individual display elements 402. Multiple display modules 400 can be arranged to form a larger display. Each of the four individual display elements 402 can in many respects be similar to the display element 100 discussed herein in relation to Figures 1-3. In one approach, the display module 400 can be configured such that the four individual display elements 402 share the same variable volume fluid reservoir and the same actuator. By sharing the same variable volume fluid reservoir and the same actuator, the states of the individual display elements 402 can be controlled in unison. That is, the individual display elements 402 can have the same state. This can be advantageous where the desired size of the pixel is greater than the size of the four individual display elements 402. The surface area of the four individual display elements 402 can then be combined to act as a single pixel. As an example, the size (DI x D2) of the display module 400 can be about 34 mm x 34 mm. In some instances, DI and D2 can have values between about 5 mm and about 100 mm.

[0041] While the display module 400 includes four display elements, it is understood that the display module 400 could include fewer or additional display elements, or elements having different shapes. Furthermore, the distribution of the individual display elements can be different from the even row and column distribution shown in Figure 2. For example, the display elements can be distributed such that the number of rows of display elements is different from the number of columns of display elements. In some instances, the display elements can be arranged in a staggered manner, where display elements in one row are staggered in relation to the display elements in at least one neighboring row. In some instances, the display elements can be arranged in concentric polygonal patterns, or in a random pattern. In other instances, the truncated square shape of each display element could be shaped as a different polygon such as a hexagon or octagon.

[0042] The display module 400 includes an optically transparent window 410, a first spacer 450, an optically transparent membrane 414, a second spacer 452, four pistons 422, four springs 434 and at least one deformable membrane 420. The variable volume optical chamber can be formed created by the first spacer 450 between the optically transparent window 410 and the optically transparent membrane 414. A housing 454 can have a first opening 456 and a second opening 458. The housing 454 can accommodate the four springs 434, the four pistons 422, the second spacer 452, the optically transparent membrane 414, the first spacer 450 and optionally the optically transparent window 410. The optically transparent window 410 can be adhered to the housing 454 at the first opening 456. The at least one deformable membrane 420 can be coupled to the housing 454 at the second opening 458. The housing 454 also can include the remainder of the spring mechanisms including a cylinder, a connecting rod, and the connecting rod conduit. The housing 454 also can include conduits 460 that fluidly connect the variable volume optical chambers and the variable volume fluid reservoir. The optically absorptive fluid can be filled into the variable volume fluid reservoir through one or more sealable ports in the at least one deformable membrane 420. The at least one deformable membrane 420 can include an actuator receiving area 462 which is coupled with an actuator. The actuator receiving area 462 shown in Figure 4 is an indent where the actuator engages with the at least one deformable membrane 420. However, the indent is only an example. The actuator receiving area 462 could have any shape that allows effective engagement with the actuator and can depend on the shape and size of the actuator. While Figure 4 shows the display module 400 including four springs 434 in conjunction with connecting rods of four pistons 422, the display module 400 can in addition or alternatively include the embodiments discussed above in relation to Figures 2 and 3. For example, the display module 400 can include the peripheral springs (e.g., the first peripheral spring 202 and the second peripheral spring 204) discussed above in relation to Figure 2 and/or the optically transparent membrane 114 with hinge 138 discussed above in relation to Figure 3.

[0043] Figure 5 shows an exploded view of an example actuator assembly 500 that can be used in conjunction with the display elements discussed herein. In particular, the actuator assembly 500 can be used to provide an actuation force to the at least one deformable membrane of the variable volume fluid reservoir. The actuator assembly 500 can include a motor mount 502, an actuation motor 504 and an actuation motor circuitry 506. The motor mount 502 can house the actuation motor 504 and the actuation motor circuitry 506 and can be coupled with the display module by way of fasteners 510. The actuation motor 504 can be a stepper motor with a reciprocating member 508, which can be coupled, directly or indirectly, with the at least one deformable membrane of the display element. For example, one end of the reciprocating member 508 can be positioned at the actuator receiving area 462 of the at least one deformable membrane 420 shown in Figure 4. The actuation motor 504 can retract or extend the reciprocating member 508 to remove or impart an actuation force on the at least one deformable membrane. The actuation motor circuitry 506 can receive signals for actuation of the display element from a control circuitry of the display element and can transform those signals into electrical signals that control the actuation motor 504 to move the reciprocating member 508 in the desired position. For example, the actuation motor circuitry 506 may receive from the control circuity a signal indicating actuation of the display element. In response, the actuation motor circuitry 506 can generate appropriate signals which when applied to the actuation motor 504 to cause the actuation motor 504 to extend the reciprocating member 508 against the at least one deformable membrane. In some instances, an actuator interface unit 568 can be positioned between the reciprocating member 508 and the actuator receiving area 462 of the at least one deformable membrane 420. The actuator interface unit 568 can provide for any size and shape mismatch between the reciprocating member 508 and the actuator receiving area 462.

[0044] The actuator assembly 500 shown in Figure 5 is only an example, and other types of actuators can also be employed. For example, electroactive polymers can be used to provide the actuation force to the at least one deformable membrane. At least one example of actuators utilizing electroactive polymers is discussed in WO 2020/087028, entitled “Display Techniques Incorporating Fluidic Actuators and Related Systems and Methods,” which is incorporated by reference herein in its entirety. Other actuator examples can include solenoid actuators, magnetic actuators, DC motor actuators, AC motor actuators, piezoelectric actuators, thermal actuators, electrostatic actuators, chemical actuators, pneumatic actuators, hydraulic actuators, shape memory alloy actuators, linear actuators, or rotary actuators.

[0045] Figure 6 shows an exploded view of another display module 600. In particular, Figure 6 shows a color display module 600. The color display module 600, similar to the display module 400 shown in Figure 4, includes four individual display elements. However, unlike the display elements of the display module 400, which included display elements of the same color, the display elements of the color display module 600 can include a front assembly 610, a plurality of pistons 622, a plurality of springs 634, a housing 654, at least one deformable membrane 620, a plurality of actuator interface units 668, an actuator housing 670, a plurality of actuator motors 672, actuation motor circuitry 674, and an actuator housing 676. The front assembly 610 can include an optically transparent window, one or more optically transparent membranes, spacers positioned between the optically transparent window and the one or more optically transparent membranes to create variable volume optical chambers for each display element.

[0046] The color display module 600 also can include a plurality of conduits 662 which are at least in part formed in the spacer and the optically transparent membrane to create a conduit for fluid communication between the reservoirs and the variable volume optical chambers. Each display element can include at least two conduits, one for each color fluid. For example, each display element can include at least three conduits one for each of the three primary colors (e.g., cyan, magenta, and yellow). Each display element can include three separate variable optical chambers that are positioned on top of each other and below the front assembly 610. In one example, the front assembly 610 can include three optically transparent membranes that are separated by spacers from each other and another spacerthat separates the topmost optically transparent membrane from the optically transparent window, forming three separate variable volume optical chambers. When the pistons 622 (each of which includes the moveable reflective surface) move towards the optically transparent windows, the pistons force the optically absorptive fluids from each of the three chambers and into their respective reservoirs, thereby entering an observed reflector state.

[0047] The front assembly 610, the pistons 622 and the springs 634 can be housed within the housing 654. On the other side of the housing 654 the at least one deformable membrane 620 cover various cavities 678 that form the reservoirs for the optically absorptive fluids of each color. As an example, three cavities 678 per display element can be utilized to store the three different colors of the optically absorptive fluids. Each of the cavities 678 can include a portion of the conduit that fluidically couples the cavity with a corresponding variable volume optical chamber. The at least one deformable membrane 620 can include three actuator receiving areas 680 corresponding to the three reservoirs. The actuator receiving areas 680 couple directly or indirectly with their respective actuators.

[0048] The actuator housing 670 houses the actuator interface units 668 which form mechanical interfaces between the actuators 672 and the actuator receiving areas 680. The plurality of actuator motors 672 are coupled with the actuator interface units 668 and to the actuation motor circuitry 674. Figure 6 shows twelve actuator motors 672, three each for the four display elements. Each actuation motor can be precisely controlled to apply a predefined magnitude of actuation force and displacement to the at least one deformable membrane 620. The predefined magnitude of actuation force and displacement can correspond to the amount of fluid that needs to be pushed into the variable volume optical chamber for the desired color. For example, to display a composite black color, the three actuation motors for each of the cyan, magenta, and yellow colors can be activated to push the three colors into their respective variable volume optical chambers below the optically transparent window. This will push the piston 622 away from the optically transparent window, and the volume between the optically transparent window and the piston 622 can be occupied by the three fluids. The combination of the three color liquids can result in a composite black state. Other colors also can be displayed by controlling the amount of fluid of each color that is pushed into the respective variable volume optical chamber. In particular, the amount of color can correspond to the thickness of the fluid between the moveable reflective surface on the piston 622 and the optically transparent window according to Beer-Lambert absorption characteristics. Different thicknesses of different colors can result in different color combinations. Thus, the actuator motors 672 can be precisely controlled to cause the desired thickness of color fluid in the respective variable volume optical chamber. While Figure 6 shows the color display module 600 including springs 634 in conjunction with connecting rods of the pistons 622, the color display module 600 can in addition or alternatively include the embodiments discussed above in relation to Figures 2 and 3. For example, the color display module 600 can include the peripheral springs (e.g., the first peripheral spring 202 and the second peripheral spring 204) discussed above in relation to Figure 2 and/or the optically transparent membrane 114 with hinge 138 discussed above in relation to Figure 3.

[0049] In some examples, the at least one deformable membrane (discussed above in relation to Figures 1-6) can include one or more sealable ports to enable introduction of the optically absorptive fluid into the display element. One aspect of filing the display element with an optically absorptive fluid is to reduce the risk of formation of air bubbles or pockets within the reservoir, the conduit, or the optical chamber. In one approach, the at least one deformable membrane can include two sealable ports. In this approach, one port is used to introduce the fluid into the reservoir, while a low pressure is maintained at the second port to pull air or gas from the reservoir until the display element is completely filled with the fluid. Once the fluid is filled in the reservoir, the port is sealed. In another approach, only a single sealable port can be utilized. In this approach, first a low pressure is generated outside of the single port. This low pressure pulls out air from the display element creating a vacuum. Thereafter, the port is coupled with a fluid source. The vacuum inside the display element pulls in the fluid. Thereafter, the port is again coupled to a low-pressure source that pulls out remaining air or gas followed by another coupling with the fluid source. This process is repeated several times until all the air or gas is removed and the display element is filled with the fluid. In some examples, the ports can be sealed using a curable adhesive activated by ultraviolet or visible light exposure. In some other examples, a shaped plug or a ball forced into the port can be utilized to plug the port.

[0050] Figure 7 shows a portion of a cross-sectional view of an example display module 700 with edge lighting. In particular, the display module 700 includes at least one light source 775 embedded at an edge of the optically transparent window 110 to provide edge lighting for the display element. The at least one light source 775 can be positioned along a periphery of the optically transparent window 110 such that light emitted by the at least one light source 775 is totally internally reflected by a front surface of the optically transparent window 110 with light leakage directed towards the moveable reflective surface 116. In some instances, light emitting diodes (LEDs) can be utilized to implement the at least one light source 775. The at least one light source 775 can be used in conjunction with at least one lens that narrows the emission pattern of the at least one light source 775. In addition, the lens can be oriented such that the light is directed towards the moveable reflective surface 116 to reduce the risk of the light emitting from the front surface of the optically transparent window 110. While Figure 7 shows the display module 700 including the spring 134 in conjunction with the connecting rod 124 of the piston 122, the display module 700 can in addition or alternatively include the embodiments discussed above in relation to Figures 2 and 3. For example, the display module 700 can include the peripheral springs (e.g., the first peripheral spring 202 and the second peripheral spring 204) discussed above in relation to Figure 2 and/or the optically transparent membrane 114 with hinge 138 discussed above in relation to Figure 3. Furthermore, the edge lighting discussed above in relation to Figure 7 can be employed in the examples discussed above in relation to Figures 4-6. In particular, the display module 400 can include the at least one light source 775 embedded at an edge of the optically transparent window 410. Similarly, the color display module 600 can include the at least one light source 775 embedded at the edge of the optically transparent window in the front assembly 610.

[0051] Figure 8 shows an exploded view of an example display module 800 including edge lighting. In particular, Figure 8 shows a display module that includes at least one light source 875 positioned along one or more edges of the optically transparent window 410. For example, the display module 800 includes four light sources positioned along the periphery of the four sides of the optically transparent window 410. In some instances, more than one light source can be incorporated per side. In some instances, only one light source can be incorporated. Unlike the display module 700 shown in Figure 7, where the display element included its own light source, in the display module 800 shown in Figure 8, the light sources are shared with four display elements. In some other instance, multiple display modules can share a single light source. Similar features can be incorporated in the color display module 600 discussed above in relation to Figure 6.

[0052] Figure 9 shows a cross-sectional view of a portion of a display module including a hinged optically transparent membrane. In particular, Figure 9 shows a cross-sectional view of the optically transparent membrane 414 of the display module 400 shown in Figure 4. The optically transparent membrane 414 is positioned between the piston 422 and the optically transparent window 410. The optically transparent membrane 414 includes a moveable portion 972, a fixed portion 974 and a hinge 970 coupled with the moveable portion 972 and the fixed portion 974. The fixed portion 974 is adhered to a sidewall or a surface of the display module 400. The hinge 970 is a U-shaped structure that allows the moveable portion 972 to move towards the optically transparent window 410 when pushed by the piston 422 or move away from the optically transparent window 410 when displaced by the optically absorptive fluid 108 entering the variable volume optical chamber 102 formed between the optically transparent membrane 414 and the optically transparent window 410. While the hinge 970 has a single U- shaped structure, it is understood that this is only one example. For example, the hinge can be similar to the hinge 138 discussed above in relation to Figure 3. In some instances, more than one U-shaped structure can be formed in series between the moveable portion 972 and the fixed portion 974. The optically transparent membrane 414 including the moveable portion 972, the fixed portion 974, and the hinge 970 can also be incorporated in the color display module 600 discussed above in relation to Figure 6, as well as the display element 100 discussed above in relation to Figure 1.

[0053] Figure 10 shows a cross-sectional view of an example color display element 1000. In particular, the color display element 1000 can be utilized as a pixel or a sub-pixel of a reflective display device such as, for example, the color display module 600 discussed above in relation to Figure 6. Several features of the color display element 1000 are similar to the features discussed above in relation to the display element 100 shown in Figure 1. To that extent, the common features are labeled with the same reference numerals. Unlike the display element 100 in Figure 1, which includes a single optically absorptive fluid 108, the color display element 1000 includes three optically absorptive fluids. Specifically, the color display element 1000 includes a first optically absorptive fluid 108a, a second optically absorptive fluid 108b, and a third optically absorptive fluid 108c. The color display element 1000 also includes a first variable volume optical chamber 102a, a second variable volume optical chamber 102b, and a third variable volume optical chamber 102c for accommodating the first optically absorptive fluid 108a, the second optically absorptive fluid 108b, and the third optically absorptive fluid 108c, respectively. The color display element 1000 includes a first optically transparent membrane 114a, a second optically transparent membrane 114b, and a third optically transparent membrane 114c. The first variable volume optical chamber 102a is defined by an optically transparent window facing side of the first optically transparent membrane 114a, the piston facing side of the second optically transparent membrane 114b and sidewalls of the color display element 1000. The second variable volume optical chamber 102b is defined by the optically transparent window facing side of the second optically transparent membrane 114b, the piston facing side of the third optically transparent membrane 114c, and the sidewalls of the color display element 1000. The third variable volume optical chamber 102c is defined by the optically transparent window 110, the optically transparent facing side of the third optically transparent membrane 114c, the optically transparent window 110, and the sidewalls of the color display element 1000.

[0054] The color display element 1000 also can include a first variable volume fluid reservoir 104a and a first conduit 106a that fluidically couples the first variable volume fluid reservoir 104a with the first variable volume optical chamber 102a. While not shown in Figure 10, the color display element 1000 also includes a second variable volume fluid reservoir and a second conduit fluidically coupling the second variable volume fluid reservoir with the second variable volume optical chamber 102b; and a third variable volume fluid reservoir and a third conduit fluidically coupling the third variable volume fluid reservoir with the third variable volume optical chamber 102c. The color display element 1000 can also include at least one actuator coupled with each of the variable volume fluid reservoirs to provide the actuation force and fluid displacement for the operation of the color display element 1000.

[0055] The first optically transparent membrane 114a can include a first hinge 1070a that couples the first optically transparent membrane 114a with a sidewall of the color display element 1000. Similarly, the second optically transparent membrane 114b and the third optically transparent membrane 114c can include the second hinge 1070b and the 1070c, respectively.

[0056] During operation, in the absence of an actuation force or displacement of the fluids from the variable volume fluid reservoirs, the color display element 1000 can be in the observed reflector state. In this state, the piston 122 is pushed towards the optically transparent window 110. The spring mechanism 130 can impart sufficient force on the piston 122 to cause the piston 122 to move towards the optically transparent window 110 and causing the optically absorptive fluids in each of the first variable volume optical chamber 102a, the second variable volume optical chamber 102b, and the third variable volume optical chamber 102c to be pushed out into their respective variable volume fluid reservoirs. As a result, substantially no optically absorptive fluids are positioned between the moveable reflective surface 116 and the optically transparent window 110.

[0057] The color display element 1000 can be switched to the covered reflector state or the intermediate state by activating one or more actuators associated with any one of the three variable volume fluid reservoirs. For example, a controller can activate the one or more actuators associated with the first at least one deformable membrane 120a. The actuator can cause the deformation of the first variable volume optical chamber 102a and the displacement of the first optically absorptive fluid 108a from the first variable volume fluid reservoir 104a to the first variable volume optical chamber 102a via the first conduit 106a. The displacement of the first optically absorptive fluid 108a into the first variable volume optical chamber 102a can cause the piston 122 to move away from the optically transparent window 110. In a similar manner, actuators associated with the at least one deformable membrane of the second variable volume fluid reservoir and/or the at least one deformable membrane of the third variable volume fluid reservoir can be activated to introduce the respective fluid into the respective variable volume optical chamber.

[0058] In some instances, the order in which the optical chambers are arranged can be based on the scattering properties of the corresponding fluid. For example, the fluid with the highest scattering can be positioned nearer to the piston 122 than fluids with relatively lower scattering. [0059] Figures 11A and 11B show two states of another example display module 1100. Specifically, Figure 11 A shows the display module 1100 in covered reflector state while Figure 1 IB shows the display module 1100 in an observed reflector state. The display module 1100 is similar to the display element 100 discussed above in relation to Figure 1. However, unlike the display element 100 which includes a piston 122 with a connecting rod 124, the display module 1100 includes a stiffener 1122 attached to the optically transparent membrane 114. The stiffener 1122 provides rigidity to the optically transparent membrane 114 such that the spring mechanism 1124 can be devoid of the connecting rod 124. The optically transparent membrane 114 can be flexible to allow the movement of the stiffener 1122 between the covered reflector state shown in Figure 11 A and the observed reflector state shown in Figure 1 IB. A moveable reflective surface 1116 can be positioned on the surface of the stiffener 1122 that faces the optically transparent window 110. In some respects, the spring mechanism 1124 of the display module 1100 is similar to the spring mechanism discussed above in relation to Figure 2, in that the spring mechanism may not include a connecting rod positioned inside the spring 134. The display module 1100 can have at least a portion of the moveable reflective surface 1116 attached or adhered to the optically transparent membrane 114. For example, the optically transparent membrane 114 can include at least one portion along the periphery of the 114 that is not attached to the stiffener 1122 and a portion that is attached to the stiffener 1122. This portion not attached to the stiffener 1122 can be flexible enough to allow a full range of motion for the portion attached to the stiffener 1122 from the observed reflector state to the covered reflector state. The stiffener 1122 can maintain the portion of the optically transparent membrane 114 attached to the stiffener 1122 stiff or flat such that when the stiffener 1122 is resting against the optically transparent window 110 with the optically transparent membrane 114 therebetween, the risk of trapped optically absorptive fluid 108 between the optically transparent membrane 114 and the optically transparent window 110 is reduced. The display module 1100 can include various types of springs discussed above in relation to Figure 2.

[0060] In some applications, the optical quality of the optically absorptive fluid discussed herein may deteriorate with repeated exposure to ultra-violet light. The exposure to UV light can be expected where the display element is used as an outdoor sign or display. In some such instances, to reduce the risk of degradation of the optically absorptive fluid, the optically absorptive fluid can include UV stabilizers or antioxidants. The UV stabilizers or antioxidants can include one or more of octylmethoxycinnamate, avobenzone, liydroxybenzoates, benzotriazoles, hydroxy phenyltrazines, oxanilides, or antioxidants and free radical scavengers from the phenolic, thioester, phosphite, aminic chemical classes, or blends thereof. In some instances, a UV filter can be disposed over the surface of the optically transparent window 110 that faces the viewer.

[0061] In some instances, the optically absorptive fluid can be formed by mixing a pigment or dye with a base liquid. In some examples, the optically absorptive fluid includes at least one organic or inorganic pigment, such as quinacridone, metal phthalocyanine, or carbon black pigment or at least one phthalocyanine, acid, basic, azoic, nitro, vat, mordant, sulfur or other synthetic dye.

[0062] The discussion herein describes several aspects of the apparatus that can be implemented separately or in combination with other aspects of the disclosure without departing from the disclosure. The following lists a non-limiting set of aspects of the display device should not be confused with the claims.

[0063] Aspect 1 : This aspect includes a display apparatus, including: a variable volume optical chamber including an optically transparent window and a moveable reflective surface positioned opposite the optically transparent window, the moveable reflective surface being normally forced to push against the optically transparent window; a variable volume fluid reservoir defined by at least one deformable membrane; a conduit providing fluid communication between the optical chamber and the fluid reservoir; and an optically absorptive fluid moveable between the variable volume optical chamber and the variable volume fluid reservoir via the conduit, wherein the at least one deformable membrane is configured to deform responsive to an actuation force and reduce a volume of the variable volume fluid reservoir causing the fluid to move from the variable volume fluid reservoir to the variable volume optical chamber via the conduit, push the moveable reflective surface away from the optically transparent window, and occupy a volume between the moveable reflective surface and the optically transparent window.

[0064] Aspect 2: The apparatus according to any one of Aspects 1 and 3-20, wherein a magnitude of the actuation force is greater than a magnitude of a force normally forcing the moveable reflective surface to push against the optically transparent window.

[0065] Aspect 3: The apparatus according to any one of Aspects 1-2 and 4-20, wherein responsive to removal of the actuation force, the moveable reflective surface moves towards the optically transparent window and displaces the fluid between the moveable reflective surface and the optically transparent window into the variable volume fluid reservoir causing the at least one deformable membrane to deform and increase the volume of the variable volume fluid reservoir to accommodate the fluid pushed out of the variable volume optical chamber.

[0066] Aspect 4: The apparatus according to any one of Aspects 1-3 and 5-20, wherein removal of the actuation force includes reduction in the magnitude of the actuation force to a value that is less than the magnitude of the force normally forcing the moveable reflective surface to push against the optically transparent window.

[0067] Aspect 5: The apparatus according to any one of Aspects 1-4 and 6-20, wherein the actuation force is a mechanical force external to the variable volume fluid reservoir.

[0068] Aspect 6: The apparatus according to any one of Aspects 1-5 and 7-20, wherein the optically transparent window is rigid.

[0069] Aspect 7: The apparatus according to any one of Aspects 1-6 and 8-20, wherein a combination of the variable volume optical chamber, the variable volume fluid reservoir and the conduit form a sealed chamber enclosing the fluid at a pressure that is greater than an atmospheric pressure.

[0070] Aspect 8: The apparatus according to any one of Aspects 1-7 and 9-20, wherein the conduit is a valve-less conduit.

[0071] Aspect 9: The apparatus according to any one of Aspects 1-8 and 10-20, wherein the moveable reflective surface is positioned on a piston that is pushed towards the optically transparent window by a spring mechanism.

[0072] Aspect 10: The apparatus according to any one of Aspects 1-9 and 11-20, wherein the moveable reflective surface is mounted on a spring mechanism extending between a periphery of the moveable reflective surface and an inner surface of the variable volume optical chamber. [0073] Aspect 11: The apparatus according to any one of Aspects 1-10 and 12-20, wherein a rigid optically transparent membrane is positioned between the moveable reflective surface and the optically transparent window, the rigid optically transparent membrane mounted on a hinge extending between the rigid optically transparent membrane and an internal surface of the display apparatus, the hinge allowing the rigid optically transparent membrane to move responsive to a movement of the moveable reflective surface.

[0074] Aspect 12: The apparatus according to any one of Aspects 1-11 and 13-20, wherein the rigid optically transparent membrane includes a thermoplastic material.

[0075] Aspect 13: The apparatus according to any one of Aspects 1-12 and 14-20, wherein a flexible optically transparent membrane is positioned between the moveable reflective surface and the optically transparent window.

[0076] Aspect 14: The apparatus according to any one of Aspects 1-13 and 15-20, wherein the at least one deformable membrane includes an elastomer material.

[0077] Aspect 15: The apparatus according to any one of Aspects 1-14 and 16-20, wherein the at least one deformable membrane includes a first sealable port and a second sealable port, wherein the optically absorptive fluid is filled into the fluid reservoir via the first sealable port while simultaneously drawing air out of the variable volume fluid reservoir via the second sealable port.

[0078] Aspect 16: The apparatus according to any one of Aspects 1-15 and 17-20, further including at least one light source positioned along a periphery of the optically transparent window such that light emitted by the at least one light source is totally internally reflected by a front surface of the optically transparent window and is directed towards the moveable reflective surface.

[0079] Aspect 17: The apparatus according to any one of Aspects 1-16 and 18-20, further including an ultraviolet filter disposed over the optically transparent window.

[0080] Aspect 18: The apparatus according to any one of Aspects 1-17 and 19-20, wherein the optically absorptive fluid includes at least one of ultraviolet stabilizers or antioxidants, such as octylmethoxycinnamate, avobenzone, hydroxybenzoates, benzotriazoles, hydroxyphenyltrazines, oxanilides, or antioxidants and free radical scavengers from phenolic, thioester, phosphite, aminic chemical classes, or blends thereof.

[0081] Aspect 19: The apparatus according to any one of Aspects 1-18 and 20, wherein the optically absorptive fluid includes at least one organic or inorganic pigment, such as quinacridone, metal phthalocyanine, or carbon black pigment or at least one phthalocyanine, acid, basic, azoic, nitro, vat, mordant, sulfur or other synthetic dye.

[0082] Aspect 20: The apparatus according to any one of Aspects 1-19, further including: a flexible optically transparent membrane positioned between the moveable reflective surface and the optically transparent window; a stiffener coupled with at least a portion of the flexible optically transparent membrane; and a spring mechanism providing a force to the stiffener to push against the optically transparent window, wherein the moveable reflective surface is positioned on a surface of the stiffener facing the optically transparent window.

[0083] As will be apparent to those of skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure.

[0084] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0085] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0086] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0087] It should be noted that ratios, concentrations, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0088] When a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g., the phrase “x to y” includes the range from ‘x’ to ‘y’ as well as the range greater than ‘x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘less than x’, less than y ’, and ‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about ‘y’”.

[0089] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0. 1% to about 5%, but also include individual values (e.g., about 1%, about 2%, about 3%, and about 4%) and the subranges (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0090] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0091] The following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure.

[0092] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by”, “comprising,” “comprises”, “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, nonlimiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include examples encompassed by the term “consisting of.

[0093] As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0094] The various concepts introduced herein may be implemented in any of numerous ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

[0095] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0096] From the foregoing, it will be seen that aspects herein are well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

[0097] While specific elements and steps are discussed in connection to one another, it is understood that any element and/or steps provided herein is contemplated as being combinable with any other elements and/or steps regardless of explicit provision of the same while still being within the scope provided herein.

[0098] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

[0099] Since many possible aspects may be made without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings and detailed description is to be interpreted as illustrative and not in a limiting sense. [0100] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.