Electrophoresis is the translation of charged objects in a fluid in response to an electric field. Electrophoretic inks are useful as a medium to enable bistable, low power types of displays. Conventional electrophoretic displays feature either black and white states (by exchanging white and black charged colorant particles at the top of the display cell) or white and colored states (by moving white colorant particles in a dyed fluid up and down electrophoretically). These conventional electrophoretic displays cannot be easily extended to provide full-color displays or large format displays.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the disclosure may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present disclosure can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.
As used herein, the term “over” is not limited to any particular orientation and can include above, below, next to, adjacent to, and/or on. In addition, the term “over” can encompass intervening components between a first component and a second component where the first component is “over” the second component.
As used herein, the term “adjacent” is not limited to any particular orientation and can include above, below, next to, and/or on. In addition, the term “adjacent” can encompass intervening components between a first component and a second component where the first component is “adjacent” to the second component.
As used herein, the term “electro-optical display” is an information display that forms visible images using one or more of electrophoresis, electro-convection, electrochemical interactions, and/or other electrokinetic phenomena.
As used herein, the term “grayscale” applies to both black and white images and monochromatic color images. Grayscale refers to an image including different shades of a single color produced by controlling the density of the single color within a given area of a display.
Embodiments provide electro-optical displays including conductive line, mesh, or lattice electrodes within the display cell. The conductive line, mesh, or lattice electrodes improve the speed, flexibility, and transparency of the electro-optical displays compared to conventional electro-optical displays where transparent conductors are used for the electrodes. In addition, in electro-optical displays utilizing gate electrodes and reservoir electrodes, the conductive line, mesh, or lattice electrodes improve control of the separation between the gate and reservoir electrodes. Further, for dual colorant electro-optical displays, the conductive line, mesh, or lattice electrodes can be arranged in various geometries optimized for electroconvective flow to provide additional independent control of the dual colorants. The conductive line, mesh, or lattice electrodes improve the optical and electrical performance of electro-optical displays, which can be used for electronic skin, electronic paper, and other applications. In one embodiment, the conductive line, mesh, or lattice electrodes are made of metal, silver nanowires, carbon nanotubes, or other suitable conductors. Metal line, mesh, or lattice electrodes can be made of gold, aluminum, nickel, copper, silver, platinum, other suitable metals, alloys thereof, multi-layer structures thereof, or combinations thereof.
In one embodiment, an electrokinetic display, which is based on the combined effect of electrophoretic and electrohydrodynamic forces, includes conductive line, mesh, or lattice electrodes to connect exposed dot regions on a first side of the display and a transparent electrode on the other side of the display. The transparent electrode can be a plate electrode, a patterned electrode, and/or a segmented or pixelated electrode. In the case of a patterned, segmented, or pixelated electrode, the individual segments of the electrode can be addressed individually.
Metal line, mesh, or lattice electrodes use very thin metallic wires. By using very thin metallic wires, the compromise between the transparency and sheet resistance of the conducting materials (e.g., ITO, PEDOT) used for transparent electrodes is eliminated. For larger devices and signage applications, transparent conductors cannot provide a conductivity high enough to allow switching at interactive speeds (i.e., greater than a few tens of milliseconds). Therefore, the optical state of the entire display will not be updated at the same time, which leads to non-uniformity. Conductive line, mesh, and lattice electrodes enable the electrokinetic display architecture to be applied to large format display applications.
The conductive line, mesh, or lattice electrodes improve the transparency of electro-optical displays. The transparency is a function of the clear aperture defined as the area not occupied by conductive wires if the absorption through substrate and dielectric layers of the display is assumed to be negligible. In one embodiment, the line width of the conductive wires can be a few microns or sub-microns to maximize the clear aperture such that the transparency of the display is 90% or better.
In other embodiments, electronic displays including a stack of two electro-optic layers are provided. Each electro-optic layer can include a single colorant or dual colorants for providing a color display. The electronic display including the stack of two electro-optic layers can provide a wide viewing angle (e.g., 180°) and a large clear aperture (e.g., greater than 75%) with negligible parallax issues. This is achieved by separating the active layers of the electronic display by a distance equal to or less than one half the pixel plate size (e.g., 500 μm cell width would have no more than 250 μm of separation between active layers). Structures for both active layers can be formed simultaneously to eliminate alignment issues. By using transparent semiconductors, such as multi-component oxide (MCO) thin film transistors (TFTs) on glass or plastic substrates and by using transparent conductors, such as Indium Tin Oxide (ITO) or poly 3,4-ethylenedioxythiophene (PEDOT) electrodes, transparency of the electronic displays can reach 95%.
First substrate 102 is parallel to and opposite second substrate 112. In one embodiment, first substrate 102 or second substrate 112 include a reflective material. In another embodiment, first substrate 102 and/or second substrate 112 include an optically clear or transparent material, such as plastic (e.g., polyethylene terephthalate (PET)), glass, or other suitable material. In another embodiment, substrate 102 is coated with or comprises a reflective material. In yet another embodiment, substrate 102 is an opaque material. In still another embodiment, a light scatterer is formed on substrate 102.
First electrode 106 is a reservoir electrode and is parallel to and opposite second electrode 110. First electrode 106 includes segments of a segmented or pixelated conductor formed on substrate 102. First electrode 106 is made from any suitable conductor, such as a metal, silver nanowires, or carbon nanotubes. Second electrode 110 is a continuous, blanket, or solid plate electrode formed on second substrate 112. In other embodiments, second electrode 110 is segmented or pixelated similar to first electrode 106. In one embodiment, second electrode 110 is formed from a film of transparent conductive material. The transparent conductive material can include carbon nanotube layers, a transparent conducting oxide such as ITO (Indium Tin Oxide), or a transparent conducting polymer such as PEDOT (poly 3,4-ethylenedioxythiophene). Other embodiments use other materials that provide suitable conductivity and transparency for electro-optical display 100a. Dielectric layer 104 is formed on substrate 102 and first electrode 106.
Dielectric layer 104 is structured with recess regions 105 that allow charged colorant particles 114 to compact on exposed portions of first electrode 106 in response to a suitable bias being applied to first electrode 106 with respect to second electrode 110.
The carrier fluid within display cell 108 includes either polar fluids (e.g., water) or nonpolar fluids (e.g., dodecane). In other embodiments, anisotropic fluids such as liquid crystal is used. The fluid may include surfactants such as salts, charging agents, stabilizers, and dispersants. In one embodiment, the surfactants provide a fluid that is an electrolyte that is able to sustain current by ionic mass transport. In other embodiments, the fluid may include any suitable medium for enabling fluidic motion of charged particles.
Colorant particles 114 in the carrier fluid are comprised of a charged material in the case of an electrokinetic display. The colorant particle material should be able to hold a stable charge indefinitely so that repeated operation of the display does not affect the charge on the colorant particles. Colorant particle materials having a finite ability to hold a stable charge, however, can be used in accordance with the various embodiments while they maintain their charge. Colorant particles may have a size between several nanometers and several tens of microns and have the property of changing the spectral composition of the incident light by absorbing and/or scattering certain portions of the spectrum. As a result, the particles appear colored, which provides a desired optical effect. In other embodiments, the colorant can be a dye, which is comprised of single absorbing molecules.
Electro-optical display 100a is in a clear optical state. The clear optical state is provided by applying a negative bias to first electrode 106 relative to a reference bias applied to second electrode 110. The negative bias applied to first electrode 106 provides an electrophoretic pull that attracts positively charged colorant particles 114. As a result, colorant particles 114 are compacted on the surface of first electrode 106 within recess regions 105. With colorant particles 114 in clear fluid compacted on the surface of first electrode 106 in recess regions 105, the clear optical state is achieved.
The positively charged colorant particles 114 can be electrophoretically and convectively moved to first electrode 106 and held there by the negative bias applied to first electrode 106 relative to second electrode 110. In one embodiment, the convective flow is a transient effect caused by the ionic mass transport in the carrier fluid, without charge transfer between the carrier fluid and first electrode 106. In this case, the convective flow proceeds for a finite amount of time and facilitates the compaction of colorant particles 114 on first electrode 106 in recess regions 105. After compaction, colorant particles 114 are held on first electrode 106 within recess region 105 by electrostatic forces generated by a coupling with first electrode 106.
In another embodiment, the convective flow is induced by ionic mass transport in the carrier fluid and by charge transfer between the carrier fluid and first electrode 106 and second electrode 110. The charge transfer can occur when the carrier fluid is coupled to the electrodes either through direct contact with the electrodes or separated from the electrodes by an intermediate layer including one or more materials. In the latter case, charge transfer is facilitated by the internal electrical conductivity of the intermediate layer, either volumetric or via pinholes and other defects.
Electro-optical display 100b is in a spread color optical state having the color of colorant particles 114. The spread color optical state is provided by applying pulses or no bias to first electrode 106 relative to the reference bias applied to second electrode 110. The pulses or no bias applied to first electrode 106 spread colorant particles 114 throughout display cell 108. With colorant particles 114 in a clear fluid spread throughout display cell 108, the spread color optical state having the color of colorant particles 114 is achieved.
Electro-optical display 100c is in the clear optical state. The clear optical state is provided by applying a negative bias to first electrode 106 relative to a reference bias applied to second electrode 110. The negative bias applied to first electrode 106 provides an electrophoretic pull that attracts positively charged colorant particles 114. As a result, colorant particles 114 are compacted on the surface of passivation layer 130 adjacent to first electrode 106. With colorant particles 114 in clear fluid compacted on the surface of passivation layer 103 adjacent to first electrode 106, the clear optical state is achieved.
Each conductive line 154a and 154b includes line regions 156 and dot regions 158. In one embodiment, dot regions 158 having a greater cross-sectional width than line regions 156. Each conductive line 154a and 154b is coupled to common contact region 152 via a line region 156. Each dot region 158 is connected to an adjacent dot region 158 by a line region 156. In one embodiment, each dot region 158 is aligned with a recess region 105 as previously described and illustrated with reference to
The relative width and size of conductive hexagonal lattice structure 182 can be optimized to provide a clear aperture. In one embodiment, the width (W) 188 of each line segment is 4.0 μm, the length (L) 184 of each line segment is 73.5 μm, and the radius (R) 186 of each hexagon is 63.7 μm to provide a clear aperture of 94%. In another embodiment, the width (W) 188 of each line segment is 4.0 μm, the length (L) 184 of each line segment is 42.7 μm, and the radius (R) 186 of each hexagon is 37.0 μm to provide a clear aperture of 90%. In yet another embodiment, the width (W) 188 of each line segment is 4.0 μm, the length (L) 184 of each line segment is 29.5 μm, and the radius (R) 186 of each hexagon is 25.5 μm to provide a clear aperture of 86%. In other embodiments, other suitable values for W, L, and R are used to provide the desired clear aperture.
While
First electrode 302 is a reservoir electrode and includes a conductive common contact region 310 and conductive lines 311 coupled to common contact region 310. Conductive lines 311 include dot regions 158 and line regions 156 between dot regions 158. Gate electrode 306 includes a conductive common contact region 312 and conductive lines 313 coupled to common contact region 312. Conductive lines 313 include ring regions 314 and line regions 316 between ring regions 314. Each ring region 314 of gate electrode 306 surrounds a recess region 305 and is aligned with a dot region 158 of first electrode 302. In one embodiment, first electrode 302 and gate electrode 306 are made from the same conductive material. In one embodiment, first electrode 302 and gate electrode 306 are passivated by a dielectric passivation layer to electrically isolate first electrode 302 and gate electrode 306 from display cell 108.
Gate electrode 306 is used to control the movement of colorant particles 308 into and out of recess regions 305. Gate electrode 306 is used to control an amount of the colorant particles 308 released from recess regions 305 and moved into the wider portions of display cell 108. By controlling the amount of colorant particles 308 released from recess regions 305 of display cell 108 and moved into the wider portion of display cell 108, gate electrode 306 also controls the color perceived by a viewer of electro-optical display 300, including a variety of tones in the grayscale.
Charged colorant particles 326 and 328 in dual colorant ink are oppositely charged and each provides a different color, such as cyan and magenta. Colorants in dual colorant ink can be any combination of primary subtractive or additive colorants, such as cyan, magenta, yellow, black, red, green, blue, and white. First electrode 322 and gate electrode 330 are used to control the movement of colorant particles 326, and first electrode 324 and gate electrode 332 are used to control the movement of colorant particles 328.
In the clear optical state, a positive bias is applied to first electrode 322, a negative bias is applied to first electrode 324, and no bias is applied to gate electrodes 330 and 332 relative to a reference bias applied to second electrode 110. The positive bias applied to first electrode 322 attracts negatively charged colorant particles 326 to compact on the surface of first electrode 322. The negative bias applied to first electrode 324 attracts positively charged colorant particles 328 to compact on the surface of first electrode 324. With colorant particles 326 and 328 compacted in recess regions 105, the clear optical state is achieved.
The negative bias applied to first electrode 324 and the negative bias applied to gate electrode 332 repel negatively charged colorant particles 328. Based on the negative bias applied to first electrode 324 and on the negative bias applied to gate electrode 332, the amount of colorant particles 328 released from recess regions 105 of display cell 108 adjacent to first electrode 324 can be controlled. As a result, some of colorant particles 328 remain in the recess regions 105 as indicated by colorant particles 328a and some of colorant particles 328 pass to the wider portion of display cell 108 as indicated by colorant particles 328b. With colorant particles 326 and 328b spread in display cell 108 and colorant particles 328a compacted in recess regions 105, the second color optical state having a color based on the combination of colorant particles 326 and 328b is achieved. In other embodiments, other color optical states can be achieved by controlling the amount of colorant particles 326 and 328 released from recess regions 105.
Conductive lines 356a and 356b are coupled to common contact region 352. Dot regions 158 of conductive lines 356a are offset from dot regions 158 of conductive lines 356b. Conductive lines 358a and 358b are coupled to common contact region 354. Dot regions 158 of conductive lines 358a are offset from dot regions 158 of conductive lines 358b. Dot regions 158 of each conductive line 356a are aligned with dot regions 158 of each adjacent conductive line 358b. Dot regions 158 of each conductive line 356b are aligned with dot regions 158 of each adjacent conductive line 358a. Common contact region 352 and conductive lines 356a and 356b are used to control the movement of one colorant and common contact region 354 and conductive lines 358a and 358b are used to control the movement of another colorant in a dual color electro-optical display.
While
In the clear optical state, a positive bias is applied to first electrode 322 and a negative bias is applied to first electrode 324 relative to a reference bias applied to second electrode 110. The positive bias applied to first electrode 322 attracts negatively charged colorant particles 326 to compact on the surface of first electrode 322. The negative bias applied to first electrode 324 attracts positively charged colorant particles 328 to compact on the surface of first electrode 324. With colorant particles 326 and 328 compacted in recess regions 105, the clear optical state is achieved.
Each electrode 408 includes a plurality of conductive lines 410 to provide one pixel of electro-optical display 400. While two pixels are illustrated in
Each first color electrode 428 includes a plurality of conductive lines 432 for controlling the movement of one colorant of each pixel of electro-optical display 400. Each second color electrode 430 includes a plurality of conductive lines 434 to control the movement of another colorant of each pixel of electro-optical display 400. Conductive lines 432 and conductive lines 434 are interdigitated. In one embodiment, conductive lines 432 provide first electrode 322 and conductive lines 434 provide first electrode 324 previously described and illustrated with reference to
Each electrode 428 is individually activated through a respective transistor or switch 436 based on signals applied to data lines 424 and control lines 426. Each electrode 430 is individually activated through a respective transistor or switch 438 based on signals applied to data lines 422 and control lines 427. In this way, each individual colorant of each individual pixel of electro-optical display 420 can be controlled to provide a desired image.
As illustrated in
To provide a clear optical state as illustrated in a portion of display cell 108, a negative bias is applied to second electrode 502a relative to the reference bias applied to first electrode 106. With the negative bias applied to second electrode 502a relative to the reference bias applied to first electrode 106, negatively charged colorant particles 504 are attracted by first electrode 106 to compact in recess regions 105. To provide a spread optical state as illustrated in another portion of display cell 108, a positive bias is applied to second electrode 502b relative to the reference bias applied to first electrode 106. With the positive bias applied to second electrode 502b relative to the reference bias applied to first electrode 106, negatively charged colorant particles 504 are attracted by second electrode 502b and are spread over second electrode 502b.
To provide a clear optical state as illustrated in a portion of display cell 108, a positive bias is applied to second electrode 526a relative to the reference bias applied to first electrode 522. With the positive bias applied to second electrode 526a relative to the reference bias applied to first electrode 522, negatively charged colorant particles 504 are attracted by second electrode 526a to compact in recess regions 525. To provide a spread optical state as illustrated in another portion of display cell 108, a negative bias is applied to second electrode 526b relative to the reference bias applied to first electrode 522. With the negative bias applied to second electrode 526b relative to the reference bias applied to first electrode 522, negatively charged colorant particles 504 are attracted by first electrode 522 and are spread in display cell 108 between first electrode 522 and second electrode 526b.
Layer 562 includes a dual colorant ink (e.g., magenta and cyan), and layer 564 includes a single colorant ink (e.g., yellow). In this embodiment, first substrate 102 is reflective or includes a reflective layer. In one embodiment, the reflective layer is white. The bias applied to first electrodes 322 and 324 of first layer 542 and to second electrodes 502a and 502b of second layer 564 can be individually controlled as previously described and illustrated with reference to
Layer 582 includes a single colorant ink (e.g., magenta), layer 584 includes a single colorant ink (e.g., cyan), and layer 586 includes a single colorant ink (e.g., yellow). In this embodiment, first substrate 102 is reflective or includes a reflective layer. In one embodiment, the reflective layer is white. The bias applied to first electrode 106 of layer 582 and to second electrodes 502a and 502b of layers 584 and 586 can be individually controlled as previously described and illustrated with reference to
By using conductive lines, meshes, or lattices in electro-optical displays, the flexibility and robustness of the electrode layer is improved, which increases the overall display reliability. In addition, using conductive lines for gate electrodes can reduce shorting between the gate and reservoir electrodes since the gate electrode can be defined around the reservoir openings. Line electrodes also enable independent control of dual colorant inks by utilizing exposed dots on separate line electrodes. The exposed dots can be arranged in regular patterns that are optimized for the given spacial frequency of electro-convection to provide optimal switching and compaction for both colorants.
Further, by using conductive lines, meshes, or lattices in place of blanket transparent electrodes, the substrate can be index matched to the dielectric layer. Typically, the index of electronic ink is relatively close to that of the substrate so that the addition of a transparent electrode introduces an index discontinuity, which can contribute to optical loss. Since optical loss increases as the number of transparent electrode layers increases in a stacked architecture, the use of conductive lines, meshes, or lattices in place of transparent electrode layers removes this constraint in the overall design. Therefore, the conductive line, mesh, or lattice electrodes enhance the overall performance of the electro-optical display, thus enabling a highly performing stacked architecture.
In one embodiment, layer 606 is a layer of index matching adhesive bonding first electro-optic layer 604 to second electro-optic layer 608. In this embodiment, first electro-optic layer 604 and transparent TFT layer 602 can be fabricated separately from second electro-optic layer 608 and transparent TFT layer 610. By fabricating first electro-optic layer 604 and transparent TFT layer 602 separate from second electro-optic layer 608 and transparent TFT layer 610, the fabrication process of first electro-optic layer 604 and transparent TFT layer 602 and second electro-optic layer 608 and transparent TFT layer 610 may be simplified. In addition, each of the electro-optic layers can be individually tested prior to bonding. After each electro-optic layer has been tested, an optical adhesive or other suitable adhesive is applied to first electro-optic layer 604 and/or to second electro-optic layer 608. First electro-optic layer 604 is optically aligned with the second electro-optic layer 608 such that each pixel of first electro-optic layer 604 is aligned with a pixel of second electro-optic layer 608. The optical adhesive is then cured using ultraviolet (UV) light or thermal or other suitable method to bond the aligned electro-optic layers to each other.
In another embodiment, layer 606 is a common mid substrate. In this embodiment, the lower portion of first electro-optic layer 604 is fabricated on the top surface of the common mid substrate, and the upper portion of second electro-optic layer 608 is fabricated on the bottom surface of the common mid substrate. In this embodiment, the distance between first electro-optic layer 604 and second electro-optic layer 608 can be reduced compared to the embodiment in which the index matching adhesive is used. In addition, embossing or other suitable processes can be used during the fabrication process to align each pixel of first electro-optic layer 604 with a pixel of second electro-optic layer 608.
Electronic display 600 is a transparent display including a dual layer stack that provides print-like color. Transparent TFT layer 602 includes a transparent substrate and TFTs. In one embodiment, transparent TFT layer 602 also includes transparent capacitors for driving first electro-optic layer 604. The TFTs in layer 602 are electrically coupled to electrodes in the upper portion of first electro-optic layer 604 to modulate one or two primary colorants within first electro-optic layer 604. The one or two primary colorants within the first electro-optic layer 604 can be modulated using electrophoretics and/or electrokinetics to provide a colored optical state or a transparent optic state for first electro-optic layer 604.
Likewise, transparent TFT layer 610 includes a transparent substrate and TFTs. In one embodiment, transparent TFT layer 610 also includes transparent capacitors for driving second electro-optic layer 608. The TFTs in layer 610 are electrically coupled to electrodes in the lower portion of second electro-optic layer 608 to modulate one or two primary colorants within second electro-optic layer 608. The one or two primary colorants within the second electro-optic layer 608 can be modulated using electrophoretics and/or electrokinetics to provide a colored optical state or a transparent optic state for second electro-optic layer 608.
In one embodiment, first electro-optic layer 604 and/or second electro-optic layer 608 each include an electro-optical display similar to the electro-optical display previously described and illustrated with reference to
In another embodiment, first electro-optic layer 604 and/or second electro-optic layer 608 each include an electro-optical display similar to the electro-optical display previously described and illustrated with reference to
In another embodiment, first electro-optic layer 604 and/or second electro-optic layer 608 each include an electro-optical display similar to the electro-optical display previously described and illustrated with reference to
Combinations of single and/or dual colorants in each electro-optic layer 604 and 608 can provide a white optical state (i.e., all layers clear), a colored optical state (i.e., independent modulation of colorants in each layer), and a dark optical state (i.e., all layers colored). In one embodiment, combinations of subtractive colorants including cyan, magenta, and yellow (CMY) or cyan, magenta, yellow, and black (CMYK) are used for the single and/or dual colorants in each electro-optic layer. In another embodiment, combinations of additive colorants including red, green, and blue (RGB) or red, green, blue, and white (RGBW) are used for the single and/or dual colorants in each electro-optic layer. In other embodiments, a hybrid of subtractive and additive colorants are used such that one electro-optic layer uses subtractive colorants while the other electro-optic layer uses additive colorants. In yet other embodiments, each electro-optic layer can use a combination of additive and subtractive colorants.
For example, in one embodiment first electro-optic layer 604 includes a single yellow colorant, and second electro-optic layer 608 includes dual cyan and magenta colorants. In another embodiment, first electro-optic layer 604 includes dual yellow and cyan colorants, and second electro-optic layer 608 includes dual magenta and black colorants. In yet another embodiment, first electro-optic layer 604 includes a single cyan colorant, and second electro-optic layer 608 includes dual yellow and magenta colorants. In yet another embodiment, first electro-optic layer 604 includes a single magenta colorant, and second electro-optic layer 608 includes dual yellow and cyan colorants. In yet another embodiment, first electro-optic layer 604 includes dual yellow and magenta colorants, and second electro-optic layer 608 includes dual cyan and black colorants. In yet another embodiment, first electro-optic layer 604 includes dual cyan and magenta colorants, and second electro-optic layer 608 includes dual yellow and black colorants. In other embodiments, other suitable single or dual colorants can be used in first electro-optic layer 604 and second electro-optic layer 608. The use of a black colorant in one of the electro-optic layers including dual colorants provides an improved black optical state compared to an electronic display that does not include a black colorant.
First electrodes 704 and second electrodes 706 are interdigitated and formed on the top surface of bottom substrate 702. In one embodiment, first electrodes 704 and second electrodes 706 are similar to interdigitated electrodes 428 and 430 previously described and illustrated with reference to
Dielectric layer 708 is formed over first electrodes 704 and second electrodes 706 and structured to provide recess regions 709 exposing portions of each first electrode 704 and each second electrode 706. In one embodiment, recess regions 709 are similar to recess regions 105 previously described and illustrated with reference to
Fourth electrode 716 is a continuous electrode formed on the top surface of common mid substrate 714. Fifth electrodes 722 are formed on the bottom surface of top substrate 724. Top substrate 724 is parallel to common mid substrate 714 and bottom substrate 702. Each fifth electrode 722 is electrically coupled to a thin film transistor formed on the bottom surface of top substrate 724. The active electrodes for the upper and lower electro-optic layers are aligned within each pixel.
Dielectric layer 720 is formed over fifth electrodes 722 and structured to provide recess regions 721 exposing portions of each fifth electrode 722. In one embodiment, recess regions 721 are similar to recess regions 709 and are aligned with recess regions 709. Pixel sidewall 718, which is also made of a dielectric material such as the dielectric material of dielectric layer 722, is formed on the bottom surface of top substrate 724 and separates adjacent pixels of electronic display 700 from each other. Each fifth electrode 722 extends between adjacent pixel sidewalls 718. Pixel sidewall 718 is aligned with pixel sidewall 710.
Bottom substrate 702, common mid substrate 714, and top substrate 724 each comprise a transparent substrate, such as a glass substrate, a plastic substrate, or a composite substrate (e.g., glass fiber, reinforced plastic, or a glass particle embedded plastic matrix). First electrodes 704, second electrodes 706, third electrode 712, fourth electrode 716, and fifth electrodes 722 each comprise a transparent conductive material, such as Indium Tin Oxide (ITO), poly 3,4-ethylenedioxythiophene (PEDOT), nanomaterial conductors (e.g., silver nanowires or carbon nanotubes), or metal mesh conductors. In one embodiment, the thin film transistors formed on bottom substrate 702 and on top substrate 724 each comprise multi-component oxide (MCO), amorphous silicon, or polysilicon. Dielectric layers 708 and 720 and pixel sidewalls 710 and 718 each comprise a transparent dielectric material. In one embodiment, the dielectric material is a dielectric resin that is patterned using an embossing process or a photolithography process.
A carrier fluid with dual colorants is provided between first and second electrodes 704 and 706 and third electrode 712. In one embodiment, the carrier fluid with dual colorants is similar to the carrier fluid with colorant particles 326 and 328 previously described and illustrated with reference to
Another carrier fluid with a single colorant is provided between fourth electrode 716 and fifth electrodes 722. In one embodiment, the carrier fluid with a single colorant is similar to the carrier fluid with colorant particles 114 previously described and illustrated with reference to
In one embodiment, the distance (as indicated at 726) between first electrodes 704 (and second electrodes 706) and fifth electrodes 722 is equal to or less than one half the width (as indicated at 728) of each fifth electrode 722, which defines the size of a single pixel. With the distance between first electrodes 704 and fifth electrodes 722 equal to or less than one half the width of each fifth electrode 722, electronic display 700 does not exhibit any serious parallax issues. In addition, by using common mid substrate 714 with continuous third electrode 712 on one side and continuous fourth electrode 716 on the other side, the fabrication process for electronic display 700 is simplified.
In this embodiment, fifth electrodes 742 and sixth electrodes 744 are interdigitated and formed on the bottom surface of top substrate 724 in a similar manner as first electrodes 704 and second electrodes 706 are formed on the top surface of bottom substrate 702. Each electrode 742 and 744 is electrically coupled to a thin film transistor formed on the bottom surface of top substrate 724 in a similar manner as each electrode 704 and 706 is electrically coupled to a thin film transistor formed on the top surface of bottom substrate 702. The active electrodes for the upper and lower electro-optic layers are aligned within each pixel.
Dielectric layer 720 is formed over fifth electrodes 742 and sixth electrodes 744 and structured to provide recess regions 721 exposing portions of each fifth electrode 742 and each sixth electrode 744. In one embodiment, recess regions 721 are similar to recess regions 709 and are aligned with recess regions 709.
A carrier fluid with dual colorants is provided between fourth electrode 716 and fifth and sixth electrodes 742 and 744. Fifth electrodes 742 are used to control the movement of one of the colorants, and sixth electrodes 744 are used to control the movement of the other one of the colorants. Thus, electronic display 740 uses dual colorants in each electro-optic layer. In one embodiment, the dual colorants of one electro-optic layer include a yellow colorant and a cyan colorant, and the dual colorants of the other electro-optic layer include a magenta colorant and a black colorant. In other embodiments, the dual colorants of each electro-optic layer include other suitable colorants as previously described with reference to
In this embodiment, each electro-optic layer is fabricated separately. Third electrode 712 is formed on the bottom surface of substrate 752. Fourth electrode 716 is formed on the top surface of substrate 756. Substrates 752 and 756 each comprise a transparent substrate, such as a glass substrate, a plastic substrate, or a composite substrate (e.g., glass fiber, reinforced plastic, or a glass particle embedded plastic matrix). After each electro-optic layer has been fabricated, substrate 756 of the upper electro-optic layer is bonded to substrate 752 of the lower electro-optic layer using index matching adhesive layer 754. Substrates 756 and 752 are aligned and bonded such that pixel sidewalls 718 are aligned with pixel sidewalls 710. Index matching adhesive layer 754 minimizes the Fresnel reflection loss, which allows a maximum amount of light to be introduced for the electro-optic modulation.
Substrates 752 and 756 and index matching adhesive layer 754 can also be used in place of common mid substrate 714 of electronic display 740 illustrated in
In this embodiment, a dielectric layer 762 is formed over fourth electrode 716 and structured to provide recess regions 763 exposing portions of fourth electrode 716. In one embodiment, recess regions 763 are similar to recess regions 709 and are aligned with recess regions 709. A pixel sidewall 764, which is also made of a dielectric material such as the dielectric material of dielectric layer 762, is formed on fourth electrode 716 and separates adjacent pixels of electronic display 760 from each other. Pixel sidewall 764 is aligned with pixel sidewall 710.
In this embodiment, the lower electro-optic layer includes first electrodes 722, a dielectric layer 774 including recess regions 775, and pixel sidewalls 776. First electrodes 772 are formed on the top surface of bottom substrate 702. Each first electrode 772 is electrically coupled to a thin film transistor formed on the top surface of bottom substrate 702. The active electrodes for the upper and lower electro-optic layers are aligned within each pixel. Dielectric layer 774 is formed over third electrode 712 and structured to provide recess regions 775 exposing portions of third electrode 712. In one embodiment, recess regions 775 are similar to recess regions 763 and are aligned with recess regions 763.
Pixel sidewall 776, which is also made of a dielectric material such as the dielectric material of dielectric layer 774, is formed on third electrode 712 and separates adjacent pixels of electronic display 700 from each other. Each first electrode 772 extends between adjacent pixel sidewalls 776. Pixel sidewall 776 is aligned with pixel sidewall 764. A carrier fluid with a single colorant is provided between first electrodes 772 and third electrode 712. First electrodes 772 are used to control the movement of the single colorant.
Embodiments provide a color electronic display by stacking two electro-optic layers. By stacking two electro-optic layers, an optically efficient structure providing an improved color gamut (i.e., modulation of every color in every pixel) as well as brightness for color reflective displays is provided. A two layer color electronic display results in less absorption, scattering, and/or reflection compared to displays with more than two layers. In addition, the embodiments provide a color electronic display without parallax issues and having a wide viewing angle.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.
This patent application is a continuation-in-part of U.S. patent application Ser. No. 12/815,811, entitled “DISPLAY ELEMENT” and filed Jun. 15, 2010, which is incorporated herein by reference.
Number | Date | Country | |
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Parent | 12815811 | Jun 2010 | US |
Child | 13032234 | US |