WO2008089042A1

WO2008089042A1 - Material

Info

Publication number: WO2008089042A1
Application number: PCT/US2008/050769
Authority: WO
Inventors: David P. Markel; Sterling F. Chaffins; Kevin P. Dekam
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2007-01-19
Filing date: 2008-01-10
Publication date: 2008-07-24

Abstract

Various embodiments and methods relating to a material (30, 130, 360, 532, 538) configured to change between a first light attenuating state, a second light attenuating state and a third light emitting state in response to applied electrical fields.

Description

MATERIAL

BACKGROUND

[0001] Emissive displays operate in darkness. In contrast, reflective displays operate in the presence of ambient light, such as in daylight. Reflective displays do not operate well in darkness.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figure 1 is a schematic illustration of a display system according to an example embodiment.

[0003] Figure 2 is a front elevational view of another embodiment of a display of the display system of Figure 1 according to an example embodiment.

[0004] Figure 3 is a sectional view of the display of Figure 2 taken along line 3—3 according to an example embodiment.

[0005] Figure 4 is a front elevational view of another embodiment of a display of the display system of Figure 1 according to an example embodiment.

[0006] Figure 5 is a sectional view of the display of Figure 4 taken along line 5—5 according to an example embodiment.

[0007] Figure 6 is a sectional view of another embodiment of a display of the display system of Figure 1 illustrating the display in a first mode according to an example embodiment.

[0008] Figure 7 is a sectional view of the display of the display system of Figure 1 illustrating the display in a second mode according to an example embodiment. [0009] Figure 8 is a schematic illustration of another embodiment of the display system of Figure 1 according to an example embodiment.

[0010] Figure 9 is a sectional view of another embodiment of a display of the display system of Figure 1 according to an example embodiment.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0011] Figure 1 schematically illustrates display system 20 according to one example embodiment. Display system 20 is configured to display one or more images by emitting light or by reflecting light. Display system 20 has enhanced versatility by being able to display images in both darkness or poorly lit conditions and in bright or daylight conditions.

[0012] Display system 20 includes display 24 and display driver 26. Display 24 forms one or more visible images in response to or under control of driver 26. Display 24 includes active layer 30, electrodes or conductors 32, 34 and reflector/backlight 36. In addition to the aforementioned layers, display 24 may include other transparent or clear substrate layers (not shown). Such substrate layers provide foundations or support for the various functional layers of display 24. Such substrate layers may be formed from a dielectric transparent materials such as polyethylene terephthalate (PET), glass and others. For ease of illustration and discussion, such substrate layers have been omitted with respect to display 24 and other embodiments of display 24 described hereafter. [0013] Active layer 30 comprises a layer of material configured to be selectively actuated between least three different states including (1) an opaque state, (2) a substantially clear or transparent state and (3) a light emitting state. In the opaque state, the material of layer 30 may be either white so as to scatter or diffuse light or a light absorbing state. In the transparent state, light is permitted to pass through layer 30. In the light emitting state, the material layer30 generates or emits visible light. In the light emitting state, the material of layer 30 is also clear or transparent such that the generated visible light may escape layer 30. As a result, layer 30 provides display 24 with enhanced versatility by providing display 20 with the ability to present images in lit conditions, such as in daylight, as well as in dark or poorly lit conditions. Because layer 30 is actuatable between each of the three states, display 24 may be less complex and more compact. [0014] According to one example embodiment, layer 30 is formed from a homogenous layer of a polymer dispersed liquid crystal (PDLC) (pockets of liquid crystal material dispersed throughout a transparent polymer layer) and one or more phosphor particles or compositions configured to emit visible light in response to an applied electric field. In particular, in the absence of an electric field or in the presence of a sufficiently small electric field, the phosphor compositions remain unexcited and the PDLC attains a light attenuating or opaque state, either creamy white or colored, if dyed. In the presence of a sufficiently strong electric field, the PDLC attains a substantially clear or transparent state, permitting visible light to pass therethrough. If the frequency of the applied electric field is sufficiently high, the phosphor compositions become excited and additionally emit visible light. According to one embodiment, such phosphor compositions become excited in response to an electric field having a strength of at least about 70 Vac and a frequency of at least about 1500 Hz. In other embodiments, the phosphor compositions may be configured to become excited in response to other electric field strengths or other frequencies.

[0015] In one embodiment, layer 30 is formed by mixing components of a polymer dispersed liquid crystal with one or more phosphor materials and subsequently curing the mixture. For example, in one embodiment, material 30 may be formed by forming a pre-polymer including a mixture of a photo activator and a monomer. The photo activator or initiator may comprise MXM035 part A, commercially available from Merck Specialty Chemicals Ltd, South Hampton, England. In such an embodiment, the monomer may comprise MXM035 part B, commercially available from Merck Specialty Chemicals Ltd, South Hampton, England. According to one embodiment, this pre-polymer is subsequently mixed with liquid crystal. In one example embodiment, liquid crystal may comprise BL035, commercially available from Merck Specialty Chemicals Ltd, South Hampton, England. This PDLC mixture is then further combined with one or more phosphor compositions. The PDLC mixture and phosphor compositions are then spread to an appropriate thickness and cured by exposing the mixture to ultraviolet light such that the mixture transitions from a nematic liquid crystal phase to an isotropic liquid crystal phase. [0016] The following are example, non-limiting, formulations of the material of layer 30. All percentages given are by weight. In other embodiments, layer 30 may be formed from other formulations.

Sample Formulation A

41% liquid crystal (BL035)

35% monomer (resin) (MXM035 part B)

4.4% photo activator or initiator (MXM035 part A)

19% TGHl 400WH phosphor ink

[0017] The phosphor ink TGHl 400WH phosphor ink is commercially available from Allied Photochemical, Inc. of Kimball, Michigan. The resulting mixture was cured by exposing the mixture for approximately 7 to 10 seconds to ultraviolet light having an intensity of 7.5 amps, a 75% duty cycle and a frequency of 10 pulses per second using a Phoseon RXlO commercially available from Phoseon Technology of Hillboro, OR.

Sample Formulation B

9^73 grams of BL035 55% LC solution with 20 um spacers (what exactly are the percentages of this composition?)

0.273 grams of Durel 1PHS002 High-Efficiency Blue-Green Encapsulated EL

Phosphor.

[0018] The Durel Phosphor is commercially available from the Durel Division of Rogers Corporation, Chandler, Arizona. The 20 um spacer beads are commercially available from SEKISUI Chemical Co, Ltd.. The resulting mixture was cured by exposing the mixture for approximately 7 to 10 seconds to ultraviolet light having an intensity of 7.5 amps, a 75% duty cycle and a frequency of 10 pulses per second using a Phoseon RXlO commercially available from Phoseon Technology of Hillboro, OR. Sample Formulation C

52.28% BL035

32.75% NOA 68

12.06% prepolymer(93% MXM035 part B and 7% MXM035 part A)

2.91% IRGACure 1300

0.47% 20 um spacer beads

NOA 68 Is Commercially Available from Norland Products Inc. of Cranbury, NJ. IRGACure 1300 is from the alpha aminoketone photoinitiator class and is commercially available from CIBA Specialty Chemicals of Basel, Switzerland. The resulting mixture was cured by exposing the mixture for approximately 7 to 10 seconds to ultraviolet light having an intensity of 7.5 amps, a 75% duty cycle and a frequency of 10 pulses per second using a Phoseon PvXlO commercially available from Phoseon Technology of Hillboro, OR.

[0019] In yet other embodiments, the aforementioned phosphors may be replaced with other phosphor materials or compositions. One example of another phosphor is Luxprint 8150B commercially available from Dupont de Nemours and Company. Such phosphors may be configured to emit white light or may be configured to emit selected portions or colors of the visible spectrum.

[0020] Conductors 32 and 34 comprise electrically conductive layers of materials on opposite sides of layer 30. Electrical conductors 32 and 34 cooperate to function as a capacitor, applying an electric field across layer 30. In one embodiment, electrical conductor 32 is formed from a transparent electrically conductive material such as indium tin oxide (ITO) or (PEDOT). In other embodiments, electrical conductor 32 may be formed from other transparent electrically conductive materials. Depending upon the configuration of reflector/backlight 36, electrical conductor 34 may comprise a layer of transparent or clear electrically conductive material, similar to conductor 32, or conductor 34 may comprise an opaque electrically conductive material such as copper, aluminum, nickel and the like. As indicated by broken lines 38, in particular embodiments, one or both of electrical conductors 32 and 34 may be pixelated into discrete electrically conductive areas, portions or pixels/sub pixels that are electrically separated or insulated from one another and that are individually chargeable to distinct voltages. In such an embodiment, selected portions of layer 30 may be actuated to different states by selectively charging such pixels or sub pixels of one or both of conductors 32, 34.

[0021] Reflector/backlight 36 comprises a surface or device configured to direct light through layers 30, 32 and 34. In one embodiment, reflector/backlight 36 comprises a reflective surface. For example, in one embodiment, reflector/backlight 36 comprises a white-lambertian surface. In another embodiment, reflector/backlight 36 may comprise a colored reflective surface. In some embodiments, reflector/backlight 36 may include a changeable layer that may be actuated between different reflective states or between a reflective state and a clear or transmissive state, wherein another reflective layer is provided behind the changeable layer. For example, reflector/backlight 36 may include another PDLC layer and a static reflective layer, wherein the PDLC changes between a clear state and an opaque state in response to an applied electric field. In still another embodiment, reflector/backlight 36 may include an electro wetting layer in front of a static reflective layer, wherein the electrowetting layer is configured to change between a colored or opaque state and a clear or transparent state. In yet another embodiment, reflector/backlight 36 may include electrostatically-directed movement of nanoparticles or microparticles, wherein the layer changes between different opaque states or different reflective states.

[0022] In particular embodiments, reflector/backlight 36 may be pixelated into multiple regions or pixels provided with distinct colors. For example, in one embodiment, reflector multiple pixels, each pixel having a red colored subpixel, a green colored subpixel and a blue colored subpixel (the primary colors). In yet other embodiments, reflector/backlight 36 may comprise a specular reflector . In particular embodiments wherein conductor conductor 34 provides a reflective surface, reflector/backlight 36 may be omitted. [0023] In other embodiments, reflector/backlight 36 may comprise a backlight. For example, in one embodiment, reflector/backlight 36 may comprise a panel of light emitting diodes configured to emit white light or one or more colors of visible light. In still other embodiments, reflector/backlight 36 may be configured to emit other forms of light such as ultraviolet light or infrared light. In particular embodiments, reflector/backlight 36 may be configured to be actuated between different reflective or light providing states. For example, in one embodiment, reflector/backlight 36 may have one or more portions that are selectively actuatable between a transparent or clear state and a reflective (specular, white Lambertion or colored) state. In another embodiment, reflector/backlight 36 may have one or more portions that are selectively actuatable between a light emitting state and a reflective state or a light emitting state and a transparent state.

[0024] Display driver 26 drives or controls display 24. In particular, display driver 26 selectively applies charge to conductors 32 and 34 to control the application of an electric field across layer 30 so as to actuate material layer 30 between (1) an opaque state, (2) a transparent state or (3) a transparent and light emitting state. Display driver 26 includes voltage sources 42, 44, switches 46, 48, input 50, sensor 52 and controller 54.

[0025] Voltage sources 42 and 44 comprise sources of electrical charge electrically connected to switches 46 and 48, respectively. In one embodiment, voltage sources 42 and 44 supply predetermined voltage levels. In another embodiment, voltage sources 42 and 44 are connected to controller 54 and provide selectable levels of charge or voltage in response to control signals from controller 54.

[0026] Switches 46 and 48 comprise devices to selectively transmit or conduct electrical charge received from both sources 42 and 44 to conductor conductor 32 and 34, respectively, in response to control signals from controller 54. In one embodiment, switches 46 and 48 may comprise transistors. In other embodiments, switches 46 and 48 may comprise other switching elements such as diodes or metal-insulator-metal (MIM) devices. In those embodiments in which display 24 comprises an array of pixels or pixel cells, switches 46, 48 may be provided for each pixel, subpixel or pixel cell. In one embodiment, such switches may be provided as part of a passive matrix, wherein switches 46, 48 are grouped together distant from their associated pixels. In another embodiment, such switches may be provided as part of an active matrix, wherein switches 46, 48 are closely associated or located with respect to their associated pixels. Although driver 26 is illustrated as including a switch for each of conductors 32, 34, in other embodiments, one of conductors 32, 34 may be set at a predetermined voltage or a ground, wherein its associated switch may be omitted.

[0027] Input 50 comprises a device configured to facilitate input of commands, selections or instructions to controller 54 from an external source. In particular, input 50 is configured to facilitate input of commands for selectively applying one or more electric fields to layer 30 to actuate one or more portions of conductor 32 to a selected state depending upon current lighting conditions (different levels of darkness or lighting). In one embodiment, input 50 is configured to facilitate input of such commands from a person through a manual or voice interface. Examples of a manual interface include a keyboard, a keypad, a touch screen, one or more pushbuttons, slides, switches and the like, and a mouse or stylus. Examples of voice interfaces include a microphone and associated speech recognition software. In another embodiment, input 50 is configured to facilitate input of such commands from an external electronic device such as through a Universal Serial Bus port. In other embodiments, input 50 may be omitted.

[0028] Sensor 52 comprises one or more devices configured to sense or detect lighting conditions on a viewing side 60 of display 24. Sensor 52 generates signals and transmits such signals to controller 54 representing the sense lighting conditions. As a result, controller 54 may automatically generate control signals based upon signals from sensor 52 representing the existing lighting conditions. In one embodiment, sensor and controller 54 communicate via wires or cables. In another embodiment sensor 52 and controller 54 may include components configured to permit sensor 52 to be remote from controller 54 and to communicate with controller 54 in a wireless fashion. For example, in one embodiment, such communication may be done using infrared, radio frequency or other wireless communication methods. In other embodiments, sensor 52 may be omitted.

[0029] Controller 54 comprises one or more processing units configured to generate control signals which causes one or more selected charges to be applied to one or both of conductors 32 and 34 so as to select or control the state of one or more portions of layer 30. For purposes of this application, the term "processing unit" shall mean a presently developed or future developed processing unit that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processing unit to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. For example, controller 54 may be embodied as part of one or more application-specific integrated circuits (ASICs). Unless otherwise specifically noted, the controller is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit. [0030] In operation, controller 54 receives signals from sensor 52 indicating the presence or current lighting conditions proximate to viewing side 60 of display 24. Based upon such signals, controller 54, following instructions contained in a computer readable medium or memory, automatically selects a desired state for one or more portions of layer 30. For example, in bright or well lit conditions, controller 54 may generate control signals such that an electric field is applied across layer 30 such that layer 30 is in a clear or transparent state, permitting light to pass through layer 30 and to be reflected from reflector/backlight 36 providing an image or another image providing surface. In such bright or well lit conditions, controller 54 may alternatively generate control signals such that an electric field is applied across layer 30 or such that no electric field is applied across layer 30, wherein layer 30 is in an opaque state. As a result, the image provided by reflector/backlight 36 or the other image providing surface is concealed and the one or more images of layer 30, if any, are displayed as a result of light reflecting off of layer 30 or being absorbed by layer 30.

[0031] Alternatively, in dark or low lighting conditions, controller 54 may generate control signals such that an electric field is applied across layer 30 to activate layer 30 to a clear and a light emitting state. In those embodiments in which layer 30 includes phosphor compositions, applying an appropriate electric field at an appropriate frequency causes the phosphors to be excited and to emit visible light. In those embodiments in which the phosphor compositions emit white light upon being excited, the light may pass through conductor 34 and illuminate or reflect from reflector/backlight 36 or other image providing surfaces to display an image. In those embodiments in which the phosphor compositions emit colored light, the color of the image being reflected from reflector/backlight 36 or from another image providing surface may be illuminated and may have a different color appearance as compared to bright or well lit conditions, wherein white light is reflected to provide the image to a viewer.

[0032] In one embodiment, controller 54 may alternatively present a suggested condition or state for layer 30 based upon signals from sensor 52 to a viewer via a display, one or more light emitting diodes, voice recordings or the like for selection by a viewer prior to implementing the suggested state. As a result, the viewer may confirm or reject the suggested state for layer 30. Via input 50, the viewer may fine-tune or adjust the suggested state for layer 30. In yet another embodiment, the state of layer 30 may be controlled by controller 54 based solely upon commands received via input 50 from a viewer.

[0033] In those embodiments in which an image is formed by selectively activating pixels or sub-pixels of display 24, controller 54 may also generate such control signals for each of such pixels or some pixels based in part upon electronic image data representing an image to be displayed by display 24. In those embodiments in which one or both of conductors 32, 34 are pixelated, selected portions of layer 30 may be activated between different opaque, clear or light emitting states to modify or form a new visible image for a viewer. In those embodiments in which portions of layer 30 are provided with different phosphor compositions that emit different colors of light upon being excited, different visible images may be created by selectively activating selected portions of layer 30 between different states. In particular embodiments in which reflector/backlight 36 is also controllable or selectively actuatable to different states, controller 54 may also generate control signals controlling or selecting a state of reflector/backlight 36 as indicated in broken line 59.

[0034] Figures 2 and 3 schematically illustrate display 124, a particular example of display 24. Display 124 is configured to display one or more of multiple distinct images without employing a passive or active matrix of switches. Display 124 includes layer 130, conductors 132, 134 and reflector 136. Like layer 30, Layer 130 comprises a layer of material configured to be selectively actuated between least three different states including (1) an opaque state, (2) a substantially clear or transparent state and (3) a light emitting state. In the opaque state, the material of layer 130 may be either white so as to scatter or diffuse light or a light absorbing state. In the transparent state, light is permitted to pass through layer 130. In the light emitting state, the material layer 130 generates or emits visible light. In the light emitting state, the material of layer 130 is also clear or transparent such that the generated visible light may escape layer 130. [0035] In the particular example illustrated, layer 130 includes distinct portions which are patterned with different materials so as to form different visible images depending upon the state of layer 130. As shown by Figure 2, layer 130 includes portions 141A, 14 IB (collectively referred to as portions 141), portions 143 A, 143B (collectively referred to as portions 143) and portions 145 A, 145B (collectively referred to as portions 145). Portions 141 comprise regions or areas of layer 130 having distinct properties when layer 130 is in an opaque state. In particular, portion 141A has a distinct color as compared to portion 141B when layer 130 is in the opaque state. In one embodiment, portions 141 each comprise a polymer-dispersed liquid crystal. However, one of portions 141 has a dichroic dye while the other of portions 141 omits a dichroic dye or has a different dichroic dye. In the example illustrated, portion 141A omits a dichroic dye such that portion 14 IA is creamy or white opaque state in the absence of a sufficiently strong electric field. Portion 14 IB has a dichroic dye, such as black or a colored dye. As a result, when layer 130 is in the opaque state, light reflected from layer 130 provide a viewer with an image of portion 14 IB on a background provided by portion 141A. Although portion 141B is illustrated as being oval in shape, portion 141B may have a variety of the different shapes. Portion 14 IB may comprise a picture, a graphic, text or any other image. Although layer 130 is illustrated as including a single portion 14 IB on a background provided by portion 14 IA, in other embodiments, layer 130 may include multiple portions 14 IB. In other embodiments, portion 14 IB may be white while portion 14 IA may be colored or black.

[0036] According to one embodiment, portions 141A and 141B are patterned in distinct steps. In particular example illustrated, portion 14 IA is formed by patterning a first polymer dispersed liquid crystal and curing the polymer dispersed liquid crystal. After portion 14 IA has been cured, portion 14 IB is formed by patterning a second polymer dispersed liquid crystal including a dichroic dye and curing the second polymer dispersed liquid crystal. In other embodiments, this order of forming portion 141 may be reversed. According to one embodiment, such patterning may be performed using an ink jet printer. In other embodiments, other patterning methods such as masks or stencils may be employed for patterning. For example, in lieu of selectively depositing material, material may be selectively removed or inactivated such as using thermal or chemical techniques.

[0037] Portions 143 comprise regions or areas of layer 130 in which selectively activatable visible light emitting compositions are patterned into distinct images. For purposes of this disclosure, the term "image" shall mean any picture, drawing, symbol, text, alphanumeric symbol or design, or the like. In the example illustrated, portion 143 A is patterned in the shape of a square while portion 143B is patterned in the shape of a triangle. In other embodiments, portions 143A and 143B may patterned to form various other images.

[0038] According to one example embodiment, portions 143 are formed by patterning a phosphor composition in layer 130. According to one embodiment, portions 143 may be formed in a fashion similar to the method by which portions 141 are formed. For example, portions 143 may be formed by selectively depositing and curing such distinct areas. According to yet another embodiment, portions 143 may be formed using electrophoresis to move charged particles and dielectrophoresis to move uncharged paticles. Using electrophoresis, the phosphor compositions of portions 143A and 143B are provided with distinct charges or polarities and wherein differently charged plates in the shapes of portions 143A and 143B are positioned proximate to layer 130 while the polymer dispersed liquid crystal is in a fluid or semi-fluid state about a phosphor compositions to selectively attract and/or repel phosphor compositions to pattern the differently charged phosphor compositions. Both positive and negative affects can be used for repulsive or attractive movement, respectively. In still other embodiments, portions 143 A and 143B may be patterned into images in other fashions. [0039] Portions 145 are similar to portions 143 except that portions 145 are formed one or more phosphor compositions that are different from the phosphor compositions of portions 143. In particular, portions 145 are formed from one or more phosphor compositions that, upon being excited, emit a different color of visible light than the phosphor compositions of portions 143. Portions 145 may be formed using the same methods by which portions 143 are formed.

[0040] Conductors 132, 134 comprise layers of a electrically conductive material which serve as electrodes for applying electric field across layer 130. In the particular example illustrated, each of conductors 132 and 134 are clear or transparent layers. In one embodiment, conductors 132 and 134 may be formed from ITO or PEDOT. In other embodiments, conductors 132 and 134 may be formed from other transparent electrically conductive materials.

[0041] Reflector 136 comprises one or more layers of one or more materials which provide a surface configured to at least partially reflect visible light, wherein different portions of the surface reflect light differently so as to provide a visible image. In the example illustrated, reflector 136 includes portions 147, 149 and 151. Portions 147, 149 and 151 comprise regions or areas configured to reflect visible light differently. In the example illustrated, portions 147, 149 and 151 reflect different colors of light. For example, portion 147 is a white reflective surface while portions 149 and 151 are differently colored reflective surfaces. In one embodiment, portions 147, 149 and 151 may be formed by patterning a light absorbing or light reflective material 153 on a substrate 155. For example, in one embodiment, one or more of portions 147, 149 and 151 may be formed by inkjet printing. In other embodiments, such portions may be formed by other printing or patterning techniques.

[0042] In the particular example illustrated, portions 149 and 151 are in substantial viewing alignment with portions 143 A and 145 A, respectively. As a result, when layer 130 is in a light emitting state, light emitted by the phosphor compositions of portions 143 and 145 is more directly reflected off of portions 149 and 151, respectively. In certain embodiments, layer 130 may be selectively activated between the clear state and the clear and light emitting state to modify the color of the visible image being viewed. For example, when layer 130 is in a clear state, portion 149 may reflect red light. However, when layer 130 is in a light emitting state, portion 143 A may emit blue light. As a result, the image viewed may be a modified color comprising a mixture of the red light and a blue light.

[0043] In other embodiments, portions 149 and 151 may be offset or spaced from portions 143 A and 143B, respectively. In such an embodiment, different overall images or displays may be selectively displayed by selectively controlling the state of layer 130. For example, when layer 130 is in a clear state, a first overall display comprising light reflected from portions 149 and 151 is viewed. However, when layer 130 is in a clear and light emitting state, the first overall display is supplemented by additional images or characters provided by one or more of portions 143 A and 145 A. [0044] In operation, driver 26 (shown in Figure 1) may selectively apply an electric field across layer 130 to select which image is displayed. By reducing or eliminating electric field being applied across layer 130, driver 26 actuators layer 130 to an opaque state in which images provided by portions 141 are presented. By increasing the electric field being applied across layer 130, driver 26 may actuate layer 130 to a clear state in which images provided by portions 147, 149 and 151 are presented. By adjusting the electric field, such as by providing the electric field with an appropriate frequency, driver 26 may actuate layer 130 to a clear and light emitting state in which images provided by portions 147, 149, 151 as well as portions 143 are presented. Display 124 may be controlled to selectively present these different images using two continuous electrodes which span all of layer 130, reducing the number of switches or the complexity of driver 26.

[0045] Figures 4 and 5 schematically illustrate display 224, another embodiment of display 24. Display 224 is similar to display 124 except that display 224 includes reflector/backlight 236 in lieu of reflector 136. Those remaining elements of display 224 which correspond to elements of display 124 are numbered similarly. [0046] Reflector/backlight 236 comprises one or more layers including reflective portions 243 and 245 and backlight portion 247. Reflective portions 243 and 245 are similar to reflective portions 147 and 149, respectively. In particular, reflective portions 243 and 245 comprise surfaces or areas configured to differently reflect visible light. For example, portions 243 and 245 may reflect different colors of visible light. Portions 243 and 245 may be formed by patterning different materials 153, such as different inks upon a substrate 155.

[0047] Backlight portion 241 comprises that portion of reflector/backlight 236 configured to selectively emit visible light. In one embodiment, backlight portion 247 comprises an array of light emitting diodes (LEDs). In the example embodiment illustrated, the array of light emitting diodes are arranged or clustered in a pattern such to form an image. In other embodiments, reflector/backlight 236 may alternatively include an array of light emitting diodes uniformly spread out or dispersed across its area. In one embodiment, the light emitting diodes of portion 241 emit a single color of light. In other embodiments, the light emitting diodes may be configured to selectively emit different colors of light at different times. In yet other embodiments, a first portion of the light emitting diodes of backlight portion 241 emit a first color of light while a second portion of light emitting diodes of portion 241 emit a second color of visible light. In other embodiments, other light emitting elements may be employed. [0048] Figures 6 and 7 schematically illustrate display 324, another embodiment of display 24. For ease of illustration, FIGURES 6 and 7 illustrate a single pixel 300 of display 324. According to one exemplary embodiment, display 324 includes a plurality of such pixels 300 positioned generally adjacent to one another. Each pixel 300 generally includes back substrate 340, reflective conductor 342, conductor 345, front substrate 350, conductor 355, active layer 360 and coating layers 365. Back substrate 340 serves as a support for reflective conductor 342. In one embodiment, back substrate 340 comprises dielectric material such as polyethylene terephthalate (PET) or glass. In other embodiments, back substrate 340 may be formed from other materials. [0049] Reflective conductor 342 comprises a layer of visible light reflecting material supported by back substrate 340. According to one example embodiment, conductor 342 is formed from a transmissive color filter material formed on top of a reflective metallic film such as aluminum. In other embodiments, conductor 342 may be formed from other materials such as reflective color patterns. For example, colored dots may be patterned upon substrate 340 by inkjet printing. In still other embodiments, light transmissive color filter materials may be provided adjacent to conductor 355, such as between front substrate 350 and conductor 355. In another embodiment, reflective conductor 342 may alternatively be configured so as to reflect substantially all light without substantially filtering or absorbing light.

[0050] As shown by FIGURE 6, for each pixel 300, reflective conductor 342 is partitioned or divided into distinct reflector elements 342a, 342b and 342c. Reflector elements 342a, 342b and 342c are configured to reflect distinct colors or wavelengths of visible light such as cyan, magenta and yellow colored light, respectively. In other embodiments, reflector elements 342a, 342b and 342c may comprise distinctly colored filters, such as red, green and blue filters, respectively, over a reflective layer. Although reflector elements 342a, 342b and 342c are illustrated as generally be located proximate to back substrate 340, reflector elements 342a, 342b and 342c may alternatively be located adjacent to active layer 360 or between active layer 360 and back substrate 340 while still permitting conductor 345 to operate as described below. [0051] Conductor 345 comprises a layer of electrically conductive material configured to be electrically charged so as to apply an electric field across active layer 360. Conductor 345 includes distinct electrically conductive portions or elements 345a, 345b, 345c configured to selectively apply distinct voltages across active layer 360 to control the opacity or trans lucency of adjacent portions of active layer 360. In the particular embodiment illustrated, conductor elements 345a, 345b and 345c are formed from the transparent or translucent electrically conductive materials and overlie reflector elements 342a, 342b and 342c of reflective conductor 342. For example, one embodiment, conductor 345 may comprise a conductive material such as indium tin oxide (ITO) or polyethylenedioxythiophene (PEDOT). In other embodiments, conductor elements 345a, 345b and 345c may themselves be configured to reflect different colors of light such as red, green and blue or such as cyan, magenta and yellow, enabling reflective conductor 342 to be omitted. In other embodiments, reflector elements 342a-342c may themselves be electrically conductive, permitting reflector elements 342a, 342b and 342c to be positioned on conductor elements 345a- 345c, respectively, adjacent active layer 360. In other embodiments, conductor 345 may be formed from other electrically conductive materials.

[0052] Front substrate 350 comprises a support structure for conductor 355. Front substrate 350 is formed of an optically transparent and clear dielectric material. In one embodiment, front substrate 350 may be formed from an optically clear and flexible dielectric material such as polyethylene terephthalate (PET). In other embodiments, front substrate 350 may be formed from other transparent dielectric materials that may be inflexible such as glass.

[0053] Conductor 355 comprises a layer of transparent or translucent electrically conductive material formed upon front substrate 350. Conductor 355 is configured to be charged so as to cooperate with conductor 345 to create an electric field across active layer 360. For each pixel 300, conductor 355 is partitioned into distinct portions or elements 355a, 355b and 355c configured to be independently charged to distinct voltages to create differing electrical fields across active layer 360. In one embodiment, conductor 355 comprises a transparent conductor such as indium tin oxide (ITO) or polyethylenedioxythiophene (PEDOT). In other embodiments, other transparent conductive materials may be used. Conductor 355 and conductor 345 are each electrically connected to driver26 (shown in Figure 1) or another similar driver which controls the charges created across conductors 345 and 355.

[0054] In one embodiment, conductor elements 345a-345c and elements 355a-355c of each pixel 300 are configured to be independently charged. In one embodiment, conductor elements 345a-345c and conductor elements 355a-355c of each of pixels 300 are electrically connected to a voltage source by an active matrix of electrical switching devices provided in conductor 345, back substrate 340 or another active back plane. Examples of switching devices may include thin film transistors and metal-insulator- metal devices.

[0055] In other embodiments, conductor elements 345a-345c of each pixel 300 may be configured to be independently charged to distinct voltages with the other conductor elements not configured in this fashion. In such an embodiment, conductor 355 may alternatively comprise a single continuous layer of electrically conductive material extending opposite to conductor elements 345a-345c. In another embodiment, conductor elements 355a-355c of each pixel 300 may be configured to be independently charged with the other conductor elements not configured in this fashion. In such an embodiment, conductor elements 345a-345c may alternatively be replaced with a single continuous layer of electrically conductive material extending across each of reflector elements 342a-342c.

[0056] Active layer 360 comprises a layer of material configured to change its transparency, reflectivity and light emissivity in response to changes in an applied voltage or charge. Like layer 30 (shown in Figure 1), active layer 360 is configured to change from a transparent state, allowing light to pass through active layer 360 and to be reflected from at least one of reflector elements 342a-342c of conductor 345, to a generally opaque state in which light is absorbed by active layer 360 and to a transparent and light emitting state. According to one example embodiment, active layer 360 may be comprised of a dichroic dye doped polymer dispersed liquid crystal (PDLC) 371 in which pockets of liquid crystal material are dispersed throughout a transparent polymer layer and further in which phosphor compositions 373 are mixed or otherwise dispersed. [0057] Active layer 360 is generally disposed between conductors 345 and 355. In one embodiment, active layer 360 is a layer of material continuously extending and captured between conductors 345 and 355. For each pixel 300, active layer 360 includes regions 360a, 360b and 360c. Regions 360a-360c generally extend between conductor elements 345a, 355a, conductor elements 345b, 355b and conductor elements 345c, 355c, respectively, and independently respond to voltage changes across the corresponding conductor elements by changing trans lucency. Regions 360a, 360b and 360c are generally situated across from reflector elements 342a, 342b and 342c, respectively. As a result, the opacity or translucency of regions 360a, 360b and 360c effects how much, if any, incident light may reach and be reflected off of reflector elements 342a, 342b and 342c, respectively.

[0058] Coating layer 365 generally comprises one or more layers deposited or otherwise formed on front substrate 350 opposite to conductor 355. Coating layer 365 may comprise a front plane diffuser and may include an anti-reflection layer such as anti-glare surface treatment, an ambient rejection layer, such as a plurality of optical band pass filters such as those commercially available from 3M, or a series of micro lenses and/or partial diffuse layers. In other embodiments, coating layer 365 may be omitted.

[0059] FIGURES 6 and 7 illustrate operation of display 324. FIGURE 6 illustrates one of pixels 300 in a light-absorbing state such that the image reflected from display 324 has a black or darkened portion corresponding to pixel 300. As shown by FIGURE 6, a zero voltage is applied across each of conductor elements 345a, 355a, 345b, 355b and conductor elements 345c, 355c. As a result, active layer 360 between each pair of opposite conductor elements is in a substantially opaque state in which light, such as ambient light 370, is absorbed such that little if any of ambient light 370 is reflected from pixel 300. Alternatively, the polymer dispersed liquid crystal material 371 may be dyed so as to reflect particular colors of visible light.

[0060] FIGURE 7 illustrates one of pixels 300 of display 324 in a reflecting state. In particular, FIGURE 7 illustrates driver 26 (shown in Figure 1) generating control signals causing conductor elements 345a and 355a to be charged to create a voltage (V_sat) across region 360a of active layer 360 between conductor elements 345a and 355a. At the same time, driver 26 generates control signals which result in a voltage (including a zero voltage) being applied across regions 360b and 360c by conductor elements 345b and 355b and conductor elements 345c and 355c, respectively, such that regions 360b and 360c are opaque or partially translucent. As a result, light 322a passes through region 360a, which is substantially translucent, and through the transparent conductive material of conductor element 345a to reflect off of reflector 342a as reflected light 364 which forms part of the image from display 324. At the same time, light 322b and 322c are substantially absorbed by regions 360b and 360c prior to reaching reflector elements 342b and 342c, respectively. As a result, light 364 reflected from the particular pixel 300 has the chrominance or color of reflector 342a. In the particular example shown in which reflector 342a is red, the particular pixel 300 reflects light having a red colored wavelength.

[0061] Although the particular pixel 300 shown in FIGURE 7 is illustrated as substantially absorbing all rays of light 322b and 322c in regions 360b and 360c, respectively, while substantially reflecting all of light 322a off of reflector 342a, at other instances, one or both of light 322b and 322c may also or alternatively be reflected off of reflector elements 342b and 342c as a result of driver 26 generating control signals causing voltages to be applied across regions 360b and 360c by conductor elements 345b, 355b and conductor elements 345c, 355c, respectively. In particular embodiments, the voltage applied across one or more of regions 360a-360c of each pixel 300 may be created so as to vary the amount of light 322a-322c absorbed by regions 360a-360c and the amount or percent of light 322a-322c reflected by one or more of reflector elements 342a-342c, respectively. For example, voltages may be applied across regions 360a-360c of the pixel 300 shown in FIGURE7 such that portions or percentages of light 322a-322c are reflected by two or more of reflector elements 342a- 342c. Multiple chrominances or colors may be reflected from pixel 300 by combining different intensities of light reflected from two or more of reflector elements 342a-342c. [0062] In dimly lit environments, driver 26 (shown in Figure 1) may cause the electric fields applied across the selected regions 360 to have an appropriate frequency such that the phosphor compositions are excited and emit visible light. Rather than relying upon light 322 from the environment, display 324 may produce its own light. Because electrical fields are applied across some of cells 300 to activate some of cells 300 to translucent and light emitting states while other cells 300 remain in active or dark, display 324 has darker black points and greater contrast. [0063] In those embodiments in which layer 360 is provided with phosphor compositions that emit different colors of light, rather than white light, selective excitation of the phosphor compositions within regions 360 may be used to selectively modify colors provided by the particular pixel 300. In bright or well lit environments, phosphor compositions within regions 360 may be selectively excited to selectively adjust the brightness of a particular pixel cell 300. In those embodiments in which region 360a includes a phosphor composition configured to emit red light, in which region 360b includes a phosphor composition configured to emit green light and in which region 360c includes a phosphor composition configured to emit blue light upon being excited, color filters or color reflector elements may be omitted. In such embodiments, the particular color provided by a particular pixel cell 380 controlled by selectively applying an electric field across one or more regions 360 such that a particular color of visible light is emitted.

[0064] Figure 8 schematically illustrates display system 420, another embodiment of display system 20 (shown in Figure 1). Display system 420 includes display 424 and display driver 426. Display 424 is similar to display 24 (shown in Figure 1) except that display 424 additionally includes active layer 440, conductors 442, 444 and dielectric layer 446. Active layer 440 comprises a layer of one or more materials configured to change between a clear or transmissive state and a visible light reflecting state in response to an applied electric field. According to one embodiment, layer 440 may comprise a reversible electroplating solution, wherein the solution actuates between a specular reflective state and a clear or transmissive state. Examples of such a solution include a homogeneous mixture, of solid consistency, comprising (a) a hydrosoluble salt or a hydrosoluble mixture of salts of at least one metal which can be cathodically deposited from an aqueous solution of one of its simple or complex ions, (b) at least one initially hydrosoluble film- forming polymer resin, (c) water, and (d) an auxiliary redox couple; the constituents (a), (b), (c), (d) selected in a group allowing plastic or viscoelastic deformability.. In such an embodiment, because layer 440 may be actuated to a specular reflective state, a greater amount of light emitted by light emitting elements, such as phosphors, in layer 30, is reflected towards viewing side 60, providing a brighter display. At the same time, layer 440 may be actuated to a clear or transmissive state, permitting light to pass through layer 440 and to be reflected off of reflector/backlight 36 which may comprise a lambertion reflector. As a result, display 424 is well-suited for daylight conditions. In yet other embodiments, layer 440 may comprise other solutions or materials which change between a clear state and a reflective state in response to applied electric fields. Examples of other materials include suspended particle switching, reflective polarizers and electrostatically-directed deposition of microparticles or nanoparticles.

[0065] Conductors 442 and 444 comprise transparent are clear electrical conductors which serve as electrodes for applying an electric field across layer 440. In one embodiment, conductors 442 and 444 may comprise ITO or PEDOT. In other embodiments, layers for 42 and 444 may be formed from other electrically conductive materials having sufficient electrical conductivity to serve as electrodes for creating an electric field across layer 440.

[0066] Dielectric layer 446 comprises one or more layers of one or more transparent or clear dielectric materials separating conductors 34 and 442. Layer 446 facilitates charging conductors 34 and 442 to distinct charges such that distinct electrical fields may be created across layers 30 and 440. Examples of materials from which layer 446 may be formed include PES, PEN, or other flexible or inflexible transparent substrate capable of holding ITO, PEDOT, PANi, or other transparent conductors. [0067] In other embodiments, conductor 442 and layer 446 may be omitted, wherein electric fields are applied across layers 30 and 440 using conductor 34. For example, a first electric field may be applied across layer 30 using conductor 32 and 34. A second electric fields may be applied across layer 440 using conductors 34 and 444. [0068] Display driver 426 is similar to display driver 26 (shown in Figure 1) except that display driver 426 additionally includes voltage sources 452, 454 and switches 456, 458. Voltage sources 452, 454 comprise sources of electrical charge electrically connected to switches 456 and 458, respectively. In one embodiment, voltage sources 452 and 454 supply predetermined voltage levels. In another embodiment, voltage sources 452 and 454 are connected to controller 54 and provide selectable levels of charge or voltage in response to control signals from controller 54. [0069] Switches 456 and 458 comprise devices to selectively transmit or conduct electrical charge received from both sources 452 and 454 to conductor layer 442 and 444, respectively, in response to control signals from controller 54. In one embodiment, switches 456 and 458 may comprise transistors. In other embodiments, switches 456 and 458 may comprise other switching elements such as diodes or metal-insulator-metal (MIM) devices. In those embodiments in which display 424 comprises an array of pixels or pixel cells, switches 456 and 458 may be provided for each pixel, sub-pixel or pixel cell. In one embodiment, such switches may be provided as part of a passive matrix, wherein switches 456 and 458 are grouped together distant from their associated pixels. In another embodiment, such switches may be provided as part of an active matrix, wherein switches 456 and 458 are closely associated or located with respect to their associated pixels. Although driver 426 is illustrated as including a switch for each of conductors 442, 444, in other embodiments, one of conductors 442, 444 may be set at a predetermined voltage or a ground, wherein its associated switch may be omitted. [0070] In operation, controller 54 generates control signals which control states of layers 30 and 440. In particular embodiments in which reflector/backlight 36 is also controllable or selectively actuatable to different states, controller 54 may also generate control signals controlling or selecting a state of reflector/backlight 36 as indicated in broken line 459. In one embodiment, controller 54 may generate control signals based upon sense lighting conditions as determined by sensor 52. In another embodiment, controller 54 may generate control signals at least in part upon commands received via input 50. In those embodiments in which an image is formed by selectively asked to aiding pixels are some pixels of display 424, controller 54 may also generate such control signals for each of such pixels or some pixels based in part upon electronic image data representing an image to be displayed by display 424. [0071] Figure 9 schematically illustrates display 524, another embodiment of display 24 (shown in Figure 1). Display 524 is configured to present or display images in variable manners depending upon existing lighting conditions. For ease of illustration, Figure 9 illustrates a single pixel or pixel cell 500. According to one exemplary embodiment, display 524 includes a plurality of such pixels 500 positioned generally adjacent to one another. Each pixel 500 generally includes active layer 532, conductors 534, 536, active layer 538, conductor 539, active layer 540, conductor 542, filter 544 and reflector/backlight 36. Like layer 30, active layer 532 comprises a layer of material configured to be selectively actuated between least three different states including (1) an opaque state, (2) a substantially clear or transparent state and (3) a clear and light emitting state. In the opaque state, the material of layer 532 may be either white so as to scatter or diffuse light or a light absorbing state. In the transparent state, light is permitted to pass through layer 532. In the light emitting state, the material layer 532 generates or emits a first primary color of visible light. In the light emitting state, the material of layer 532 is also clear or transparent such that the generated visible light may escape layer 532. According to one embodiment, layer 532 includes a material comprising a polymer dispersed liquid crystal and one or more phosphor compositions mixed therein.

[0072] Conductors 534 and 536 conduct electrical charge received from a driver, such as driver 426 (shown in Figure 4) and apply an electric field across layer 532 to actuate the materials of layer 532 between the different states. Conductors 534 and 536 are both formed from one or more transparent or clear electrically conductive materials such as ITO or PEDOT. In the particular example illustrated, conductor 534 comprises a single conductive layer extending across layer 532. Conductor 536 is pixelated into conductor elements 550A, 550B and 550C (collectively referred to as elements 550). Conductor elements 550 are electrically insulated or separated from one another by intermediate dielectric spacers 551 and are connected to one or more voltage sources by separate switches, enabling elements and 552 week individually and independently charged two distinct voltages with respect to conductor 534. As a result, different electric fields may be applied across region 553A (located between conductor 534 and element 550A), region 553B (located between conductor 534 and element 550B) and region 553C (located between conductor 534 and element 550C) to actuate such regions to different states.

[0073] Active layer 538 is substantially similar to layer 532 except that layer 538 includes a distinct phosphor composition which emits a different color of visible light upon being excited in response to an appropriate applied electric field. In one embodiment, layer 538 may include a PDLC which is substantially similar to the PDLC of layer 532. In other embodiments, layer 538 may have a PDLC which is dyed to a distinct color as compared to the PDLC material of layer 532. [0074] Conductor 539 comprises a layer of electrically conductive material. In one embodiment, the electrically conductive material is transparent such as ITO or PEDOT. Like conductor 536, conductor 539 is pixelated into conductor elements 560A, 560B and 560C (collectively referred to as conductor elements 560). In one embodiment, conductor elements 560 correspond to and are insubstantial alignment with conductor elements 550. Conductor elements 560 are electrically insulated or separated from one another by dielectric spacers 561 and are connected to one or more voltage sources by separate switches (not shown), enabling elements 550 to be individually and independently charged to distinct voltages with respect to conductor 534. As a result, different electric fields may be applied across region 563 A (located between conductor 534 and element 560A), region 563B (located between conductor 534 and element 560B) and region 563C (located between conductor 534 and element 560C) to actuate such regions to different states.

[0075] Layer 540 comprises a layer of one or more materials configured to change between a clear or transmissive state and a visible light reflecting state in response to an applied electric field. According to one embodiment, layer 540 may comprise a reversible electroplating solution, wherein the solution actuates between a specular reflective state and a clear or transmissive state in response to an applied electric field. Examples of such a solution include: a homogeneous mixture, of solid consistency, comprising (a) a hydrosoluble salt or a hydrosoluble mixture of salts of at least one metal which can be cathodically deposited from an aqueous solution of one of its simple or complex ions, (b) at least one initially hydrosoluble film-forming polymer resin, (c) water, and (d) an auxiliary redox couple; the constituents (a), (b), (c), (d) selected in a group allowing plastic or viscoelastic deformability. In such an embodiment, because layer 45 may be actuated to a specular reflective state, a greater amount of light emitted by light emitting elements, such as phosphors, in layer 532 or 538, is reflected towards viewing side 60, providing a brighter display. At the same time, layer 540 may be actuated to a clear or transmissive state, permitting light to pass through layer 540 and to be reflected off of reflector/backlight 36 which may comprise a lambertion reflector. As a result, display 524 is well-suited for daylight conditions. In yet other embodiments, layer 540 may comprise other solutions are materials which change between a clear state and a reflective state in response to applied electric fields. Examples of other materials include suspended particle switching, reflective polarizers and electrostatically-directed deposition of microparticles or nanoparticles.

[0076] Conductor 542 is similar to conductor 534. Conductor 542 comprises a layer of electrically conductive material extending across layer 540. Conductor 542 is electrically connected to a voltage source and an independent switch (not shown), permitting conductor 542 to be charged to a distinct charged with respect to one or more of conductor elements 560 so as to apply one or more electric fields across layer 540. Because conductor 539 is pixelated, distinct electric fields may be applied across region 573A (located between conductor 542 and element 560A), region 573B (located between conductor 542 and element 560B) and region 573C (located between conductor 534 and element 560C) to actuate such regions to different states. [0077] Filter 544 comprises a layer of one or more materials configured to filter out selected wavelengths of light while permitting other selected wavelengths of light to pass therethrough. In the example embodiment illustrated, filter 544 In one about them in, filter 544 may be formed from dyes, pigments, particles, polarized films, Bragg filter, Bragg reflector, photonic crystal, etc. In other embodiments, filter 544 may be formed from other materials. In other embodiments, filter 544 may be omitted. [0078] Overall, display 524 comprises a display capable of operating in varying lighting conditions. In addition, display 524 is configured to provide multiple presentation possibilities. For example, by selectively applying electric fields across regions by 553, 563 and 573, various colored images may be presented. Images presented by display 524 may have colors provided by the color of the PDLC of layer 532 when in an opaque state, the color of light emitted by the phosphor compositions of layer 532 when excited, the color of the PDLC of layer 538 when in an opaque state, the color of light emitted by the phosphor compositions of layer 538 when excited, and the one or more colors provided by filter 544. Various combinations of colors for the image may be presented to depending upon the combination of electric fields applied across regions 553, 563, and 573.

[0079] According to one embodiment, the phosphor compositions of layer 532 may be configured to emit a first primary color, the phosphor compositions of layer 538 may be configured to emit a second primary color and filter 544 may be configured to filter all but a third primary color of visible light. As a result, by selectively applying electric field across regions 553, 563 and by actuating layer 540 to a clear state, pixel 500 may present a variety of different colors resulting from a mixture of the primary colors. In one embodiment, the PDLC of layer 532 may be dyed with the first primary color and the PDLC of layer 538 may be dyed with the second primary color. In well lit conditions or daylight conditions, display 524 may present a variety of colors using the three primary colors (red, green and blue) provided by layers 532, 538 and filter 544 without energizing phosphors of display 524. At the same time, in poor lit conditions, layer 540 may be activated to a specular reflective state, enhancing brightness of display 524.

[0080] In other embodiments, display 524 may have other configurations to provide even greater versatility or to reduce complexity. For example, in particular embodiments, filter 544 may be omitted, wherein the phosphor compositions of layers 532 and 538, when excited, emit the first two primary colors and wherein the PDLC of at least one of layers 532 and 538 reflect the third primary color when in an opaque state. In yet other embodiments, filter 544 may be replaced with a reflective layer which reflects the third primary color. In such an embodiment, reflector/backlight 36 may be omitted. In still other embodiments, layer 540 may be omitted. In yet other embodiments, layer 532 and conductor 536 may be omitted where fewer colors for images presented by display 524 are satisfactory. If greater colors are desired, additional layers 532 or 538 and conductor 536 may be stacked. [0081] Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising: a material (30, 130, 360, 532, 538) configured to change between a first light attenuating state, a second light attenuating state and a third light emitting state in response to applied electrical fields.

2. The apparatus of claim 1 , wherein the first light attenuating state is substantially opaque to visible light and the second light attenuating state is substantially transmissive to visible light.

3. The apparatus of any one of claims 1-2, wherein the material (30, 130, 360, 532, 538) comprises a polymer dispersed liquid crystal and at least one phosphor homogenously dispersed amongst the polymer liquid crystal.

4. The apparatus of any one of claims 1-3 further comprising: first conductors (32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539) on a first side of the material (30, 130, 360, 532, 538), each of the first conductors (32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539) being chargeable to distinct charges; at least one second conductor(32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539) on a second side of the material (30, 130, 360, 532, 538); at least one voltage source (42, 44, 452, 454) ; a controller (54) configured to generate control signals; and switches (46, 48, 456, 458) electrically coupled between the least one voltage source (42, 44, 452, 454) and each of the first conductors (32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539), wherein the switches (46, 48, 456, 458) selectively transmit electrical charge to the first conductors (32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539) in response to the control signals to change a first portion of the material (30, 130, 360, 532, 538) to the first state and a second portion of the material (30, 130, 360, 532, 538) to either the second state or the third state.

5. The apparatus of claim 4, wherein the first portion of the material (30, 130, 360, 532, 538) includes a first phosphor configured to emit a first color of visible light and wherein the second portion of the material (30, 130, 360, 532, 538) includes a second phosphor configured to emit a second different color of visible light.

6. The apparatus of any one of claims 4-5 further comprising colored reflector or filter surfaces proximate to the material (30, 130, 360, 532, 538).

7. The apparatus of any one of claims 4-6, wherein the first conductors (32, 34, 132, 134,345, 355, 442, 444, 536, 534, 539) include a first conductor opposite a red reflector or filter, a second conductor opposite a green reflector or filter and a third conductor opposite a blue reflector or filter.

8. The apparatus of claim 4 further comprising a dynamic reflector.

9. The apparatus of claim 4 further comprising a backplane configured to change between different opaque states in response to an applied electric field.

10. A method comprising: transmitting light through a material (30, 130, 360, 532, 538) and reflecting the visible light back through the material (30, 130, 360, 532, 538) in a first illuminated environment; and emitting light from the material (30, 130, 360, 532, 538) in a second less illuminated environment.