HK1086348B - Method and device for manipulating color in a display - Google Patents

Abstract

A method and device for manipulating color in a display is disclosed. In one embodiment, a display comprises interferometric display elements formed to have spectral responses that produce white light. In one embodiment, the produced white light is characterized by a standardized white point.

Description

Method and apparatus for manipulating color in display

Technical Field

The technical field of the invention relates to micro-electromechanical systems (MEMS).

Background

Microelectromechanical Systems (MEMS) include micromechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. One type of MEMS device is known as an interferometric modulator. An interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. One plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metal film separating the stationary layer by an air gap.

Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their characteristics can be exploited in improving existing products and creating new products that have not yet been developed.

Disclosure of Invention

The system, method, and apparatus of the present invention each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the invention, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description of certain embodiments" one will understand how the features of this invention provide advantages over other display devices.

One embodiment is a display device. The apparatus includes a plurality of interferometric modulators. The plurality of interferometric modulators includes at least one interferometric modulator configured to output red light, at least one interferometric modulator configured to output green light, and at least one interferometric modulator configured to output blue light. The red, green, and blue light are mixed to produce the output white light having a standardized white point.

One embodiment is a display device. The apparatus comprises at least one display element including a reflective surface configured to be positioned at a distance from a partially reflective surface. The at least one display element is selected to produce white light characterized by a standardized white point.

Another embodiment is a display device. The apparatus includes a plurality of display elements, each display element including a reflective surface configured to be positioned at a distance from a partially reflective surface. The plurality of display elements are configured to output white light characterized by a standardized white point.

Another embodiment is a method of manufacturing a display. The method includes forming at least one display element configured to output light. Forming a display element includes forming a partially reflective surface and a reflective surface configured to be positioned at a distance from the partially reflective surface. The forming at least one display element is such that the white light produced by the at least one display element is characterized by a standardized white point.

Another embodiment is a method of manufacturing a display. The method includes forming a plurality of display elements configured to output light. Each of the plurality of display elements includes a reflective surface configured to be positioned at a distance from a partially reflective surface. The forming display elements characterizes white light generated by the plurality of display elements as a normalized white point.

Another embodiment is a display device. The apparatus includes first means for selectively reflecting light having a first color. The apparatus further includes second means for selectively reflecting light having a second color. The apparatus further includes third means for selectively reflecting light having a third color. The light reflected by the first, second and third means mixes to produce white light characterized by a standardized white point.

Another embodiment is a display device. The apparatus includes means for reflecting light and means for partially reflecting light. The means for reflecting light and the means for partially reflecting light comprise means for modulating light. The light modulating means is configured to interferometrically generate white light characterized by a standardized white point.

Another embodiment is a display device. The apparatus includes means for reflecting light and means for partially reflecting light. The means for reflecting light and the means for partially reflecting light comprise means for displaying. The display means is configured to output white light characterized by a standardized white point.

Drawings

FIG. 1 is an isometric view depicting a portion of one embodiment of an interferometric modulator display in which a movable reflective layer of a first interferometric modulator is in a released position and a movable reflective layer of a second interferometric modulator is in an actuated position.

FIG. 2 is a system block diagram illustrating one embodiment of an electronic device incorporating a 3 × 3 interferometric modulator display.

FIG. 3 is a diagram of movable mirror position versus applied voltage for one exemplary embodiment of an interferometric modulator of FIG. 1.

FIG. 4 is an illustration of a set of row and column voltages that may be used to drive an interferometric modulator display.

FIG. 5A illustrates an exemplary frame of display data in the 33 interferometric modulator display of FIG. 2.

FIG. 5B illustrates one exemplary timing diagram that may be used to write the frame of FIG. 5A to the row and column signals.

Fig. 6A is a cross-sectional view of the device of fig. 1.

FIG. 6B is a cross section of an alternative embodiment of an interferometric modulator.

FIG. 6C is a cross-sectional view of another alternative embodiment of an interferometric modulator.

FIG. 7 is a side cross-sectional view of an interferometric modulator illustrating the optical path through the modulator.

FIG. 8 is a graph illustrating the spectral response of one embodiment that includes cyan and yellow interferometric modulators to produce white light.

FIG. 9 is a side cross-sectional view of the interferometric modulator having a layer of material that selectively transmits light of a particular color.

FIG. 10 is a graph illustrating the spectral response of an embodiment that includes a green interferometric modulator and a "magenta" color filter layer to produce white light.

11A and 11B are system block diagrams illustrating one embodiment of a visual display device comprising a plurality of interferometric modulators.

Detailed Description

Various embodiments include displays that include interferometric display elements formed to produce white light having selected spectral properties. One embodiment includes a display that produces white light by using interferometric modulators configured to reflect cyan and yellow light. Another embodiment includes a display that produces white light by using an interferometric modulator that reflects green light by reflecting the green light through a filter that selectively transmits magenta light. Embodiments also include displays that reflect white light characterized by a standardized white point. The white point of such a display may be different from the white point of the light illuminating the display.

The following detailed description is directed to certain specific embodiments of the invention. However, the invention can be embodied in a multitude of different ways. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. As will be apparent from the following description, the invention may be implemented in any device that is configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual or pictorial. More specifically, it is contemplated that the present invention may be implemented in or associated with a variety of electronic devices such as, but not limited to: mobile telephones, wireless devices, Personal Data Assistants (PDAs), handheld or portable computers, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, computer monitors, auto displays (e.g., odometer display, etc.), cockpit controls and/or displays, display of camera views (e.g., display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., display of images on a piece of jewelry). MEMS devices having similar structures as described herein may also be used in non-display applications such as electronic switching devices.

FIG. 1 illustrates one embodiment of an interferometric modulator display comprising an interferometric MEMS display element. In these devices, the pixels are in either a bright or dark state. In the bright ("on" or "open") state, the display element reflects a significant portion of incident visible light to a user. When in the dark ("off" or "closed") state, the display element reflects little incident visible light to the user. Depending on the embodiment, the light reflectance properties of the "on" and "off" states may be reversed. MEMS pixels can be configured to reflect predominantly at selected colors, allowing for a color display in addition to black and white.

FIG. 1 is an isometric view depicting two adjacent pixels in a series of pixels of a visual display, wherein each pixel comprises a MEMS interferometric modulator. In certain embodiments, an interferometric modulator display comprises a row/column array of these interferometric modulators. Each interferometric modulator includes a pair of reflective layers positioned at a variable and controllable distance from each other to form a resonant optical cavity with at least one variable dimension. In an embodiment, one of the reflective layers is movable between two positions. In the first position, referred to herein as the released state, the movable layer is positioned at a relatively large distance from the partially fixed reflective layer. In the second position, the movable layer is positioned in closer proximity to the partially reflective layer. Incident light reflected from the two layers interferes constructively or destructively depending on the position of the movable reflective layer, producing either a fully reflective or non-reflective state for each pixel.

The depicted portion of the pixel array in FIG. 1 includes two adjacent interferometric modulators 12a and 12 b. In the interferometric modulator 12a on the left, the movable highly reflective layer 14a is explicitly in a released position at a predetermined distance from the fixed partially reflective layer 16 a. In the interferometric modulator 12b on the right, the movable highly reflective layer 14b is explicitly in an actuated position adjacent to the fixed partially reflective layer 16 b.

The fixed layers 16a, 16b are electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more layers of chromium and indium tin oxide on a transparent substrate 20. These layers are patterned into parallel strips and may form row electrodes in a display device as described further below. The movable layers 14a, 14b may be formed as a series of parallel strips of one or more deposited metal layers (perpendicular to the row electrodes 16a, 16b) deposited on top of posts 18 and an intervening sacrificial material deposited between the posts 18. When the sacrificial material is etched away, the deformable metal layer is separated from the fixed metal layer by a defined air gap 19. Highly conductive and reflective materials such as aluminum may be used as the deformable layer, and these strips may form column electrodes in a display device.

With no applied voltage, the cavity 19 remains between the layers 14a, 16a, and the deformable layer is in a mechanically relaxed state, as illustrated by the pixel 12a in FIG. 1. However, when a potential difference is applied to a selected row and column, the capacitance formed at the intersection of the row and column electrodes of the corresponding pixel will be charged, and electrostatic forces pull the electrodes together. If the voltage is high enough, as illustrated by the pixel 12b on the right in FIG. 1, the movable layer deforms and is forced against the fixed layer (a dielectric material, not illustrated in this figure, may be deposited on the fixed layer to prevent shorting and control the separation distance). The operating state (behavior) is the same regardless of the polarity of the applied potential difference. In this manner, row/column actuation that can control the reflective-non-reflective pixel states is analogous in many ways to conventional LCD and other display technologies.

FIGS. 2-5B illustrate exemplary processes and systems for using an array of interferometric modulators in a display application. FIG. 2 is a system block diagram illustrating one embodiment of an electronic device that may incorporate aspects of the present invention. In the exemplary embodiment, the electronic device includes a processor 21, which may be any general purpose single-or multi-chip microprocessor such as an ARM, Pentium, or other microprocessor、PentiumII、Pentium III、Pentium IV、PentiumPro、8051、MIPS、Power PC、ALPHAOr any special purpose microprocessor such as a digital signal processor, microcontroller, or programmable gate array. As is conventional in the art, the processor 21 may be configured to execute one or more software modules. In addition to executing an operating system, the processor may be configured to execute one or more software applications, including a web browser, a telephone application, an email program, or any other software application.

In one embodiment, the processor 21 may also be configured to communicate with an array controller 22. In one embodiment, the array controller 22 includes a row driver circuit 24 and a column driver circuit 26 that provide signals to a pixel array 30. The cross-sectional view of the array illustrated in FIG. 1 is shown in FIG. 2 by line 1-1. For MEMS interferometric modulators, the row/column actuation protocol may take advantage of the hysteresis properties of these devices illustrated in FIG. 3. It may require, for example, a 10 volt potential difference to cause a movable layer to deform from the released state to the actuated state. However, when the voltage is reduced from that value, the movable layer maintains its state as the voltage drops back below 10 volts. In the exemplary embodiment of FIG. 3, the movable layer does not release completely until the voltage drops below 2 volts. There is thus a range of voltages, about 3 to 7 volts in the example shown in FIG. 3, where there is a window of applied voltage within which the device is stable in either the released or actuated state. This is referred to herein as the "hysteresis window" or "stability window". For a display array having the hysteresis properties of FIG. 3, the row/column actuation protocol may be designed to expose pixels in the strobed row to be actuated to a voltage difference of about 10 volts and pixels to be released to a voltage difference of close to 0 volts during row strobing. After the strobe, the pixels are exposed to a steady state voltage difference of about 5 volts such that they remain in whatever state the row strobe put them in. After being written, each pixel sees a potential difference within the "stability window" of 3-7 volts in this example. This characteristic makes the pixel design illustrated in fig. 1 stable under the same applied voltage conditions in either an actuated or released pre-existing state. Since each pixel of the interferometric modulator, whether in the actuated or released state, is essentially a capacitor formed by the fixed and moving reflective layers, this stable state can be held at a voltage within the hysteresis window with almost no power dissipation. Essentially no current flows into the pixel if the applied potential is fixed.

In typical applications, a display frame may be created by asserting the set of column electrodes in accordance with the desired set of actuated pixels in the first row. A row pulse is then applied to the row 1 electrode, actuating the pixels corresponding to the asserted column lines. Thereafter, the asserted set of column electrodes is changed to correspond to the desired set of actuated pixels in the second row. Thereafter, a pulse is applied to the row 2 electrode, actuating the appropriate pixels in row 2 in accordance with the asserted column electrodes. The row 1 pixels are unaffected by the row 2 pulse, and remain in the state they were set to during the row 1 pulse. This process may be repeated for the entire series of rows in a sequential manner to form the frame. Typically, the frames are refreshed and/or updated with new display data by continually repeating this process at some desired number of frames per second. A wide variety of protocols for driving row and column electrodes of pixel arrays to produce display frames are also well known and may be used in conjunction with the present invention.

FIG. 4, FIG. 5A and FIG. 5BFIG. 5B illustrates one possible actuation protocol for forming display frames on the 3 × 3 array of FIG. 2. FIG. 4 illustrates a possible set of column and row voltage levels that may be used for pixels exhibiting the hysteresis curves of FIG. 3. In the embodiment of FIG. 4, actuating a pixel involves setting the appropriate column to-V_biasAnd the appropriate row is set to + av, which may correspond to-5 volts and +5 volts respectively. By setting the appropriate column to + V_biasAnd the appropriate row is set to the same + av, producing a zero volt potential difference across the pixel to effect release of the pixel. In those rows where the row voltage is held at zero volts, the pixels are stable in whatever state they were originally in, while being at + V with the columns_biasOr is-V_biasIs irrelevant.

FIG. 5B is a timing diagram showing a series of row and column signals applied to the 3X 3 array of FIG. 2 which will result in the display arrangement illustrated in FIG. 5A, where actuated pixels are non-reflective. Prior to writing the frame illustrated in FIG. 5A, the pixels can be in any state, and in this example, all the rows are at 0 volts, and all the columns are at +5 volts. With these applied voltages, all pixels are stable in their existing actuated or released states.

In the frame shown in FIG. 5A, pixels (1, 1), (1, 2), (2, 2), (3, 2), and (3, 3) are actuated. To accomplish this, during a "line time" for row 1, columns 1 and 2 are set to-5 volts, and column 3 is set to +5 volts. This does not change the state of any pixels because all pixels remain in the 3-7 volt stability window. Row 1 is then strobed with a pulse that goes from 0 volts, up to 5 volts, and back down to 0 volts. This actuates the pixels (1, 1) and (1, 2) and releases the pixel (1, 3). No other pixels in the array are affected. To set row 2 to the desired state, column 2 is set to-5 volts, and columns 1 and 3 are set to +5 volts. Thereafter, the same strobe applied to row 2 will actuate pixel (2, 2) and release pixels (2, 1) and (2, 3). Again, no other pixels in the array are affected. Similarly, row 3 is set by setting columns 2 and 3 to-5 volts, and column 1 to +5 volts. The row 3 strobe sets the row 3 pixels as shown in fig. 5A. After writing the frame, the row potentials are 0, and the column potentials can remain at either +5 or-5 volts, and the display will thereafter be stable in the arrangement shown in FIG. 5A. It will be appreciated that the same procedure can be employed for arrays consisting of tens or hundreds of rows and columns. It will also be appreciated that the timing, sequence, and levels of voltages used to perform row and column actuation can be varied widely within the general principles outlined above, and the above example is exemplary only, and any actuation voltage method can be used with the present invention.

The detailed structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example, fig. 6A-6C illustrate three different embodiments of moving mirror structures. Fig. 6A is a cross-sectional view of the embodiment of fig. 1, wherein a strip of metallic material 14 is deposited on orthogonally extending supports 18. In FIG. 6B, the moveable reflective material 14 is attached to supports at the corners only, on tethers 32. In FIG. 6C, the moveable reflective material 14 is suspended from the deformable layer 34. This embodiment is advantageous because the structural design and materials used for the reflective material 14 can be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer 34 can be optimized with respect to desired mechanical properties. In addition, a layer of dielectric material 104 is formed on the fixed layer. The production of various types of interferometric devices is described in a number of publications, including, for example, U.S. published application No. 2004/0051929. A wide variety of well-known techniques can be used to produce the above-described structures containing a series of material deposition, patterning, and etching steps.

As discussed above with reference to fig. 1, modulator 12 (i.e., both modulators 12a and 12 b) includes an optical cavity formed between mirror 14 (i.e., mirrors 14a and 14b) and mirror 16 (mirrors 16a and 16b, respectively). The characteristic distance or optical path effective length d of the optical cavity determines the resonant wavelength λ of the optical cavity and thus the resonant wavelength λ of the interferometric modulator 12. One peak resonant visible wavelength λ of the interferometric modulator 12 generally corresponds to the perceived color of light reflected by the modulator 12. Mathematically, the optical path length d is equal to 1/2N λ, where N is an integer. A given resonant wavelength λ is therefore reflected by the interferometric modulator 12 having an optical path length d of 1/2 λ (N ═ 1), λ (N ═ 2), 3/2 λ (N ═ 3), and so on. The integer N may be referred to as the interference order of the reflected light. As used herein, the level of modulator 12 also refers to the level N of light reflected by modulator 12 when mirror 14 is in at least one position. For example, a first stage red interferometric modulator 12 may have an optical path length d of about 325nm, corresponding to a wavelength λ of about 650 nm. Thus, a second stage red interferometric modulator 12 may have an optical path length d of approximately 650 nm. Generally, modulators 12 with higher orders reflect light over a narrower range of wavelengths, e.g., have a higher "Q" value, thereby producing more saturated colored light. The saturation of modulator 12, which contains one color pixel, affects the properties of the display, such as the color gamut and white point of the display. For example, in order for a display using second stage modulator 12 to have the same white point or color balance as a display including a first stage modulator that reflects light of the same color overall effect (general color), second stage modulator 12 may be selected to have a different center peak light wavelength.

Note that in particular embodiments such as illustrated in fig. 1, the optical path length d is substantially equal to the distance between the mirrors 14 and 16. Where the space between the mirrors 14 and 16 contains only one gas (e.g., air) with a refractive index close to 1, the effective length of the optical path is substantially equal to the distance between the mirrors 14 and 16. Other embodiments, such as illustrated in fig. 6C, include a layer of dielectric material 104. Such dielectric materials typically have a refractive index greater than 1. In such embodiments, the optical cavity is formed to have a desired optical path length d by selecting the distance between the mirrors 14 and 16 and the thickness and refractive index of the dielectric layer 104 or any other layer between the mirrors 14 and 16. For example, in the embodiment illustrated in FIG. 6c, the optical cavity includes a dielectric layer 104 except for an air gap, and the optical path length d is equal to d₁n₁+d₂n₂Wherein d is₁Is the thickness of layer 1, n₁Is the refractive index of layer 1; similarly, d₂Is the thickness of layer 2 and n₂Being refractive fingers of layer 2And (4) counting.

In general, the color of light reflected by the interferometric modulator 12 will vary when the modulator 12 is viewed from different angles. FIG. 7 is a side cross-sectional view of the interferometric modulator 12 illustrating the optical path through the modulator 12. The color of light reflected from the interferometric modulator 12 may vary for different angles of incidence (and reflection) relative to the axis AA illustrated in FIG. 7. For example, for the interferometric modulator 12 shown in FIG. 7, the light follows an off-axis path A₁Propagating, the light is incident on the interferometric modulator at a first angle, reflected from the interferometric modulator, and propagates to an observer. When the light reaches the viewer as a result of optical interference between a pair of mirrors in the interferometric modulator 12, the viewer perceives the first color. When the observer moves or changes his/her position to change the viewing angle, the light received by the observer follows a different off-axis path a corresponding to a second angle of incidence (and reflection) different from the first angle₂And (5) spreading. The optical interference in the interferometric modulator 12 depends on the optical path length d of the light propagating within the modulator. Thus different optical paths A₁And A₂Produce different outputs from the interferometric modulator 12. As the viewing angle increases, the effective optical path of the interferometric modulator decreases according to the relationship 2d cos β ═ N λ, where is the viewing angle (the angle between the normal to the display and the incident light). As the viewing angle increases, the peak resonant wavelength of the reflected light decreases. The user thus perceives different colors depending on his or her viewing angle. As described above, this phenomenon is called "color shift". The color shift is typically identified by the color produced by the interferometric modulator 12 when viewed along axis AA by an observer.

Another consideration in the design of displays incorporating interferometric modulators 12 is the generation of white light. "white" light generally refers to light that is perceived by the human eye without including a particular color, i.e., white light is independent of hue. Black refers to the lack of color (or light) and white refers to light that includes such a broad spectral range that no particular color is perceived. White light may refer to light having a broad spectral range of visible light with near-uniform intensity. However, since the human eye is sensitive to the wavelengths of specific red, green, and blue light, white can be generated by mixing the intensities of the colored light to produce light having one or more spectral peaks (which is perceived by the eye as "white"). Furthermore, the color gamut of a display is the range of colors that the device can reproduce, for example, by mixing red, green and blue light.

A white point is a color phase of a display that is considered to be substantially neutral (gray or colorless). The characteristics of the white point of a display device may be based on a comparison between the white light produced by the device and the spectral content of the light emitted by a black body at a particular temperature ("black body radiation"). A standard black body is an idealized object that absorbs all light incident on the object and re-emits it, where the spectrum of the light depends on the temperature of the black body. For example, the blackbody spectrum at 6,500 ° K may be referred to as white light having a color temperature of 6,500 ° K. A color temperature or white point of about 5,000-10,000K is generally recognized as daylight.

The international commission on illumination (CIE) promulgates the standardized white point of a light source. For example, the light source labeled "d" refers to daylight. In particular, the standard white points D associated with color temperatures of 5,500K, 6,500K, and 7,500K₅₅、D₆₅And D₇₅Is a standard daylight white point.

A display device may be characterized by a white point of white light produced by a display. The human perception of the display due to light from other light sources is at least partially determined by the perception of white light from the display. For example, a display or light source having a lower white point (e.g., D55) may be perceived by an observer as having a yellow hue. A display with a higher temperature white point (e.g., D75) may be perceived by a user as having a "cooler" or bluer hue. It is often easier for a user to react to a display having a higher temperature white point. Thus, controlling the white point of a display desirably provides some control over the viewer's response to the display. Embodiments of the interferometric modulator array 30 may be configured to produce white light whose white point is selected to meet a standard white point under one or more desired illumination conditions.

White light may be generated by the pixel array 30 by including one or more interferometric modulators 12 per pixel. For example, in one embodiment, the pixel array 30 includes pixels of sets of red, green, and blue interferometric modulators 12. As discussed above, the color of the interferometric modulator 12 may be selected by selecting the optical path length d using the relationship d ═ N λ. Moreover, the balance or relative proportion of the colors produced by each pixel in the pixel array 30 may be further influenced by the relative reflective area of each interferometric modulator 12 (e.g., red, green, and blue interferometric modulators 12). In addition, because the modulator 12 selectively reflects incident light, the white point of the light reflected off the pixel array 30 of the interferometric modulator 12 is typically dependent on the spectral characteristics of the incident light. In one embodiment, the white point of the reflected light may be configured to be different from the white point of the incident light. For example, in one embodiment, the pixel array 30 may be configured to reflect D75 light when used in D65 daylight.

In one embodiment, the distance d and area of the interferometric modulators 12 in the pixel array 30 are selected such that the white light produced by the pixel array 30 corresponds to a particular standardized white point under expected lighting conditions, such as: in sunlight, under fluorescent light, or to form a frontlight positioned to illuminate the pixel array 30. For example, the white point of the pixel array 30 may be selected as D under a particular lighting condition₅₅、D₆₅And D₇₅. In addition, the light reflected by the pixel array 30 may have a different white point than the light of an intended or configured light source. For example, one particular pixel array 30 may be configured to reflect D75 light when viewed in D65 sunlight. More generally, the white point of a display may be selected based on an illumination source (e.g., front light) that configures the display or based on a particular viewing condition. For example, a display may be configured to be incandescent, fluorescent, or natural, for exampleThe light source has a selected white point (e.g., D55, D65, or D75) when viewed under an intended or typical illumination source. More particularly, a display for use with a handheld device, for example, can be configured to have a selected white point when viewed in sunlight. Alternatively, a display for office use may be configured to have a selected white point (e.g., D75) when illuminated by typical office fluorescent lights.

Table 1 illustrates the optical path lengths for one embodiment. In particular, Table 1 illustrates that D is generated by using modulators 12 having substantially equal reflective areas₆₅And D₇₅In two exemplary embodiments of the pixel array 30 for white light, the air gaps for the red, green, and blue interferometric modulators. Table 1 assumes a two layer (100nm Al)₂O₃And 400nm of SiO₂) The dielectric layer of (2). Table 1 also assumes that each of the red, green, and blue interferometric modulators 12 has substantially equal reflective areas. One skilled in the art will appreciate that one range of equivalent air gap distances can be obtained by varying the thickness or refractive index of the dielectric layer.

Table 1

Modulator color D65 white D75 white (bluish)

Red 200(nm) 195(nm)

Green 125(nm) 110(nm)

Blue 310(nm) 315(nm)

It should be appreciated that in other embodiments, different distances d and regions of modulator 12 may be selected to produce other standardized white points set for different viewing environments. In addition, the red, green and blue modulators 12 may also be controlled to be in a reflective or non-reflective state for different amounts of time to further change the relative balance of the reflected red, green and blue light, thereby changing the white point of the reflected light. In one embodiment, the ratio of the reflective areas of each color modulator 12 may be selected to control the white point in different viewing environments. In one embodiment, the optical path length d may be selected to correspond to a common multiple of more than one visible resonant wavelength (e.g., the first, second, or third order peaks of red, green, and blue) in order for the interferometric modulator 12 to reflect white light characterized by three visible peaks in its spectral effect. In this embodiment, the optical path length d is selected such that the white light produced corresponds to a standardized white point.

In addition to the sets of red, green, and blue interferometric modulators 12 in the pixel array 30, other embodiments include other methods of generating white light. For example, one embodiment of the pixel array 30 includes cyan and yellow interferometric modulators 12, i.e., interferometric modulators 12 having respective pitches d to produce cyan and yellow light. The mixed spectral response of the cyan and yellow interferometric modulators 12 produces light having a broad spectral response that is perceived as "white". The cyan and yellow modulators are closely positioned so that a viewer perceives such a blended response. For example, in one embodiment, the cyan and yellow modulators are arranged in adjacent rows of the pixel array 30. In another embodiment, the cyan and yellow modulators are arranged in adjacent columns of the pixel array 30.

FIG. 8 is a graph illustrating the spectral response of one embodiment that includes cyan and yellow interferometric modulators 12 to produce white light. The horizontal axis represents the wavelength of the reflected light. The vertical axis represents the relative reflectance (relative reflectance) of light incident on the modulator 12. Trace 80 illustrates the response of the cyan modulator, which is a single peak centered on the cyan portion of the spectrum between blue and green, for example. Trace 82 illustrates the response of the yellow modulator, which is a single peak centered in the yellow portion of the spectrum between red and green, for example. Trace 84 illustrates the mixed spectral response of a pair of cyan and yellow modulators 12. Although trace 84 has two peaks at the cyan and yellow wavelengths, it is well balanced across the visible spectrum so that light reflected from modulator 12 is perceived as white.

In one embodiment, the pixel array 30 includes one first level yellow interferometric modulator and one second level cyan interferometric modulator. When this pixel array 30 is viewed from progressively larger off-axis angles, the light reflected by the first order yellow modulator is shifted towards the blue end of the spectrum, e.g., the modulator at an angle has an effective d equal to the d of the first order cyan. At the same time, the light reflected by the second level cyan modulator is shifted to correspond to the light from the first level yellow modulator. Thus, as the correlation peaks of the spectrum shift, the overall mixed spectral response is broad and relatively uniform across the visible spectrum. The pixel array 30 thus produces white light over a relatively large range of viewing angles.

In one embodiment, a display having cyan and yellow modulators may be configured to produce white light having a selected normalized white point under one or more viewing conditions. For example, the spectral responses of the cyan and yellow modulators may be selected to reflect light having a white point of D55, D65, D75 or any other suitable white point under selected lighting conditions including D55, D65, or D75 light, such as sunlight for displays suitable for outdoor use. In one embodiment, the modulator may be configured to reflect light having a different white point than the incident light from a desired or selected viewing condition.

FIG. 9 is a side cross-sectional view of an interferometric modulator 12 having a layer of material 102 for selectively transmitting light of a particular color. In one exemplary embodiment, layer 102 is on the opposite side of substrate 20 from modulator 12. In one embodiment, the material layer 102 includes a magenta filter through which the green interferometric modulators 12 are viewed. In one embodiment, the material layer 102 is a dyed material. In one such embodiment, the material is a dyed photoresist material. In one embodiment, the green interferometric modulator 12 is a first stage green interferometric modulator. The filter layer 102 is configured to transmit magenta light when illuminated by a substantially uniform white light. In the exemplary embodiment, light is incident on layer 20 and the filtered light is transmitted from layer 20 to modulator 12. Modulator 12 reflects the filtered light back through layer 102. In this embodiment, light passes through layer 102 twice. In this embodiment, the thickness of the material layer 102 may be selected to compensate for and take advantage of this double filtering. In another embodiment, a front light structure may be positioned between layer 102 and modulator 12. In this embodiment, the layer of material 102 only contributes to the light reflected by the modulator 12. In these embodiments, the layer 102 is selected accordingly.

FIG. 10 is a graph illustrating the spectral response of one embodiment that includes a green interferometric modulator 12 and a "magenta" filter layer 102. The horizontal axis represents the wavelength of the reflected light. The vertical axis represents the relative spectral response of light incident on the green modulator 12 and filter layer 102 with respect to the visible spectrum. Trace 110 illustrates the response of the green modulator 12, which is a single peak centered in the green portion of the spectrum (e.g., near the center of the visible spectrum). Trace 112 illustrates the response of the magenta filter formed by the material layer 102. The trace 112 has two relatively flat portions on either side of a central u-shaped lowermost portion. Trace 112 thus represents the response of a magenta filter that selectively transmits nearly all of the red and blue light while filtering out light in the green portion of the spectrum. Trace 114 illustrates the mixed spectral response of the green modulator 12 and filter layer 102 pair. Trace 114 illustrates that the spectral response of the composition is at a reflection level that is lower than the spectral response of green modulator 12 due to the filtering of light by filter layer 102. However, the spectral response is relatively uniform across the visible spectrum such that light filtered, reflected from the green modulator 12 and the magenta filter layer 102 is perceived as white.

In one embodiment, a display having a green modulator 12 and a magenta filter layer 102 may be configured to produce white light having a selected standardized white point under one or more viewing conditions. For example, the spectral response of the green modulator 12 and the spectral response of the magenta filter layer 102 may be selected under selected lighting conditions including D55, D65, or D75 light (such as sunlight for a display suitable for outdoor use) such that the reflected light has a white point of D55, D65, D75, or any other suitable white point. In one embodiment, the modulator may be configured to reflect light having a different white point than the incident light from a desired or selected viewing condition.

11A and 11B are system block diagrams illustrating one embodiment of a display device 2040. The display device 2040 may be, for example, a cellular or mobile telephone. However, the same components of display device 2040 or slight variations thereof are also illustrative of various types of display devices, such as televisions or portable media players.

The display device 2040 includes a housing 2041, a display 2030, an antenna 2043, a speaker 2045, an input device 2048, and a microphone 2046. The housing 2041 is generally made from any of a number of manufacturing processes well known to those skilled in the art, including injection molding and vacuum forming. Further, the housing 2041 can be made from any of a variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment, the housing 2041 includes removable portions (not shown) that are interchangeable with other removable portions having different colors or containing different logos, pictures, or symbols.

The display 2030 of exemplary display device 2040 may be any of a wide variety of displays, including a bi-stable display as described herein. In other embodiments, as is well known to those of skill in the art, the display 2030 comprises a flat panel display, such as a plasma, EL, OLED, STN LCD, or TFT LCD, as described above; or a non-flat panel display such as a CRT or other tube device. However, for purposes of describing the present embodiment, the display 2030 comprises an interferometric modulator display, as described herein.

The components of one embodiment of exemplary display device 2040 are schematically illustrated in FIG. 11B. The illustrated exemplary display device 2040 includes a housing 2041 and can include additional components at least partially enclosed within the housing 2041. For example, in one embodiment, the exemplary display device 2040 includes a network interface 2027, which network interface 2027 includes an antenna 2043 coupled to a transceiver 2047. The transceiver 2047 is connected to a processor 2021 that is connected to conditioning hardware 2052. Conditioning hardware 2052 may be configured to condition a signal (e.g., filter the signal). Conditioning hardware 2052 is coupled to a speaker 2045 and a microphone 2046. The processor 2021 is also connected to an input device 2048 and a driver controller 2029. The driver controller 2029 is coupled to a frame buffer 2028 and array driver 2022, which array driver 2022 is in turn coupled to a display array 2030. A power supply 2050 provides power to all components as required by the design of the particular exemplary display device 2040.

The network interface 2027 includes the antenna 2043 and the transceiver 2047 so that the exemplary display device 2040 can communicate with one or more devices over a network. In one embodiment, the network interface 2027 may also have some processing capabilities to reduce requirements for the processor 2021. The antenna 2043 is any antenna known to those skilled in the art for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to the IEEE 802.11 standard, including IEEE 802.11(a), (b), or (g). In another embodiment, the antenna transmits and receives RF signals according to the BLUETOOTH (BLUETOOTH) standard. In the case of a cellular telephone, the antenna is designed to receive CDMA, GSM, AMPS or other conventional signals used to communicate within a wireless cellular telephone network. The transceiver 2047 pre-processes signals received from the antenna 2043 so that they may be received by and further processed by the processor 2021. The transceiver 2047 also processes signals received from the processor 2021 so that they may be transmitted from the exemplary display device 2040 via the antenna 2043.

In an alternative embodiment, the transceiver 2047 may be replaced by a receiver. In another alternative embodiment, the network interface 2027 may be replaced by an image source, which may store or generate image data to be sent to the processor 2021. For example, the image source can be a Digital Video Disc (DVD) or a hard-disc drive that includes image data, or a software module that generates image data.

The processor 2021 generally controls the overall operation of the exemplary display device 2040. The processor 2021 receives data, such as compressed image data, from the network interface 2027 or an image source and processes the data into raw image data or into a format that is readily processed into raw image data. Thereafter, the processor 2021 sends the processed data to the driver controller 2029 or frame buffer 2028 for storage. Raw data generally refers to information that identifies the image characteristics at each location within an image. For example, these image characteristics may include color, saturation, and gray-scale level.

In one embodiment, the processor 2021 includes a microprocessor, CPU, or logic unit to control operation of the exemplary display device 2040. Conditioning hardware 2052 typically includes amplifiers and filters for transmitting signals to the speaker 2045, and for receiving signals from the microphone 2046. Conditioning hardware 2052 may be discrete components within the exemplary display device 2040, or may be incorporated within the processor 2021 or other components.

The driver controller 2029 takes the raw image data generated by the processor 2021 either directly from the processor 2021 or from the frame buffer 2028 and reformats the raw image data appropriately for high speed transmission to the array driver 2022. In particular, the driver controller 2029 reformats the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning across the display array 2030. Thereafter, the driver controller 2029 sends the formatted information to the array driver 2022. Although a driver controller 2029, such as an LCD controller, is typically associated with the system processor 2021 as a stand-alone Integrated Circuit (IC), these controllers may be implemented in a variety of ways. They may be embedded in the processor 2021 as hardware, embedded in the processor 2021 as software, or fully integrated in hardware with the array driver 2022.

Typically, the array driver 2022 receives the formatted information from the driver controller 2029 and reformats the video data into a parallel set of waveforms that are applied many times per second to the hundreds and sometimes thousands of leads coming from the display's x-y matrix of pixels.

In an embodiment, the driver controller 2029, array driver 2022, and display array 2030 are appropriate for any of the types of displays described herein. For example, in one embodiment, the driver controller 2029 is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, the array driver 2022 is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, a driver controller 2029 is integrated with the array driver 2022. Such an embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, the display array 2030 is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators).

The input device 2048 allows a user to control the operation of the exemplary display device 2040. In one embodiment, input device 2048 comprises a keypad (e.g., a QWERTY keyboard or a telephone keypad), a button, a switch, a touch-sensitive screen, a pressure-or heat-sensitive membrane. In one embodiment, the microphone 2046 is an input device for the exemplary display device 2040. When the microphone 2046 is used to input data to the device, voice commands may be provided by a user to control the operation of the exemplary display device 2040.

The power supply 2050 may include various energy storage devices as are well known in the art. For example, in one embodiment, power supply 2050 is a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. In another embodiment, power supply 2050 is a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell, and solar-cell paint. In another embodiment, power supply 2050 is configured to receive power from a wall outlet.

As described above, in some implementations control programmability resides in a driver controller, which can be located in several places in the electronic display system. In some cases control programmability resides in the array driver 2022. Those skilled in the art will appreciate that the above-described optimizations may be constructed in any number of hardware and/or software components and in various configurations.

While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the spirit of the invention. It will be understood that the present invention may be embodied within a form that does not provide all of the features and advantages set forth herein, as some features may be used or practiced separately from others. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (114)

1. A display apparatus, comprising:

a plurality of interferometric modulators, the plurality of interferometric modulators comprising:

at least one interferometric modulator configured to output red light;

at least one interferometric modulator configured to output green light; and

at least one interferometric modulator configured to output blue light,

wherein the red light, the green light, and the blue light mix to produce white light having a standardized white point when illuminated by light having a different white point.

2. The apparatus of claim 1, wherein each of the plurality of interferometric modulators comprises one reflective region, and wherein the respective regions are selected to produce the white light having the normalized white point.

3. The apparatus of claim 1, wherein the standardized white point is one of standard white points D55, D65, and D75 associated with color temperatures of 5,500 ° K, 6,500 ° K, and 7,500 ° K, respectively.

4. The apparatus of claim 1, further comprising an illumination source for the plurality of interferometric modulators, the illumination source having a different white point than the white light produced with the standardized white point.

5. The apparatus of claim 1, wherein the apparatus is configured to adjust the plurality of interferometric modulators to control a white point of white light generated in different visual environments.

6. The apparatus of claim 5, wherein each of the plurality of interferometric modulators comprises a region where light is reflected, and wherein the apparatus is configured to adjust proportions of regions used to output the red, green, and blue light, respectively, to control a white point of the generated white light based on the visual environment.

7. The apparatus of claim 5, wherein the apparatus is configured to adjust the amount of time of the interferometric modulators output the red, green, and blue light, respectively, to control a white point of the generated white light based on the visual environment.

8. The apparatus of claim 5, wherein the different visual environments comprise an office environment and a daylighting environment.

9. A display apparatus, comprising:

a plurality of display elements comprising one interferometric modulator having one reflective surface configured to be positioned at a distance from one partially reflective surface,

wherein the plurality of display elements are selected to produce white light characterized by a standardized white point when illuminated by white light having a different white point.

10. The apparatus of claim 9, wherein the plurality of display elements are configured to be adjustable to control a white point of the generated white light for different visual environments.

11. The apparatus of claim 10, wherein each of the plurality of display elements comprises a region where light is reflected, and wherein regions respectively for outputting different colors of light are adjustable to control a white point of the generated white light based on the visual environment.

12. The apparatus of claim 10, wherein respective amounts of time are adjustable when the display elements modulate different colors of light, thereby controlling a white point of the generated white light based on the visual environment.

13. The apparatus of claim 10, wherein the different visual environments comprise an office environment and a daylighting environment.

14. The apparatus of claim 9, wherein the plurality of display elements further comprises a plurality of display elements having different spectral outputs that together produce white light characterized by the standardized white point.

15. The apparatus of claim 9, wherein the plurality of display elements further comprises a plurality of display elements having an area from which light is reflected, and wherein the respective areas of the display elements are selected to produce white light characterized by the standardized white point.

16. The apparatus of claim 9, wherein the plurality of display elements includes at least one display element configured to output red light, at least one display element configured to output green light, and at least one display element configured to output blue light.

17. The apparatus of claim 9, wherein the plurality of display elements are configured to output white light.

18. The apparatus of claim 9, wherein the reflective surface is positioned at a distance from the partially reflective surface to produce the white light characterized by the standardized white point.

19. The apparatus of claim 9, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

20. The apparatus of claim 9, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

21. The apparatus of claim 9, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

22. The apparatus of claim 9, further comprising an illumination source for the plurality of display elements, the illumination source having a different white point than the light reflected by the display.

23. The apparatus of claim 9, further comprising:

a processor in electrical communication with the plurality of display elements, the processor configured to process image data; and

a storage device in electrical communication with the processor.

24. The apparatus of claim 23, further comprising a driver circuit configured to send a plurality of signals to the plurality of display elements.

25. The apparatus of claim 24, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

26. The apparatus of claim 23, further comprising an image source module configured to send the image data to the processor.

27. The apparatus as recited in claim 26, wherein the image source module includes at least one of a receiver, transceiver, and transmitter.

28. The apparatus of claim 23, further comprising an input device configured to receive input data and to communicate the input data to the processor.

29. A display apparatus, comprising:

a display element comprising an interferometric modulator having a reflective surface configured to be positioned at a distance from a partially reflective surface,

one filter associated with the display element, the filter configured to selectively transmit certain visible wavelengths and substantially filter other visible wavelengths when illuminated with white light,

wherein the display elements are selected to produce white light characterized by a standardized white point when illuminated by white light having a different white point.

30. The apparatus of claim 29, wherein the reflective surface is positioned at a distance from the partially reflective surface to produce the white light characterized by the standardized white point.

31. The apparatus of claim 29, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

32. The apparatus of claim 29, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

33. The apparatus of claim 29, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

34. The apparatus of claim 29, further comprising an illumination source for the display element, the illumination source having a different white point than the light reflected by the display.

35. A display apparatus, comprising:

a display element comprising an interferometric modulator having a reflective surface configured to be positioned at a distance from a partially reflective surface,

the modulator having an optical path length between the reflective surface and the partially reflective surface, the optical path length selected to correspond to a common multiple of a plurality of visible resonant wavelengths,

wherein the display elements are selected to produce white light characterized by a standardized white point when illuminated by white light having a different white point.

36. The apparatus of claim 35, wherein the reflective surface is positioned at a distance from the partially reflective surface to produce the white light characterized by the standardized white point.

37. The apparatus of claim 35, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

38. The apparatus of claim 35, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

39. The apparatus of claim 35, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

40. The apparatus of claim 35, further comprising an illumination source for the display element, the illumination source having a different white point than the light reflected by the display.

41. The apparatus of claim 35, wherein the plurality of visible resonant wavelengths includes one red resonant wavelength, one blue resonant wavelength, and one green resonant wavelength.

42. A method of manufacturing a display, comprising:

forming a plurality of display elements comprising interferometric modulators configured to output light, wherein forming the display elements comprises forming a partially reflective surface and a reflective surface configured to be positioned at a distance from the partially reflective surface,

wherein the plurality of display elements are formed such that the white light produced by the display elements is characterized by a standardized white point when illuminated by white light having a different white point.

43. The method of claim 42, wherein the display is configured to adjust the display elements to control a white point of generated white light for different visual environments.

44. The method of claim 43, wherein each of the display elements comprises an area where light is reflected, and wherein the display is configured to adjust proportions of areas respectively for reflecting different colored light to adjust a white point of the generated white light based on the visual environment.

45. The method of claim 43, wherein the display is configured to adjust their respective amounts of time when the display elements reflect different colors of light, thereby controlling a white point of the generated white light based on the visual environment.

46. The method of claim 43, wherein the different visual environments comprise an office environment and a daylighting environment.

47. The method of claim 42, further comprising forming at least two display elements, wherein the at least two display elements are formed to have respective areas from which light is reflected and to have respective distances selected to cause the at least two display elements to produce white light characterized by the standardized white point.

48. The method of claim 42, wherein forming a plurality of display elements comprises forming at least one display element configured to output red light, at least one display element configured to output green light, and at least one display element configured to output blue light.

49. The method of claim 42, wherein the plurality of display elements are configured to output white light.

50. The method of claim 42, wherein the light reflected by the display has a different white point than light illuminating the display.

51. The method of claim 42, wherein the standardized white point is a standard white point D55 associated with a color temperature of 5,500 ° K.

52. The method of claim 42, wherein the standardized white point is a standard white point D65 associated with a color temperature of 6,500 ° K.

53. The method of claim 42, wherein the standardized white point is a standard white point D75 associated with a color temperature of 7,500 ° K.

54. A method of manufacturing a display, comprising:

forming a display element comprising an interferometric modulator configured to output light, wherein forming the display element comprises forming a partially reflective surface and a reflective surface configured to be positioned at a distance from the partially reflective surface,

forming one filter associated with the display element, the filter configured to selectively transmit certain visible wavelengths and substantially filter other visible wavelengths when illuminated with white light,

wherein the display elements are formed such that the white light produced by the display elements is characterized by a standardized white point when illuminated by white light having a different white point.

55. The method of claim 54, wherein the light reflected by the display has a different white point than light illuminating the display.

56. The method of claim 54, wherein the standardized white point is a standard white point D55 associated with a color temperature of 5,500 ° K.

57. The method of claim 54, wherein the standardized white point is a standard white point D65 associated with a color temperature of 6,500 ° K.

58. The method of claim 54, wherein the standardized white point is a standard white point D75 associated with a color temperature of 7,500 ° K.

59. A method of manufacturing a display, comprising:

forming a display element comprising an interferometric modulator configured to output light, wherein forming the display element comprises forming a partially reflective surface and a reflective surface configured to be positioned at a distance from the partially reflective surface,

wherein the modulator has an optical path length between the reflective surface and the partially reflective surface selected to correspond to a common multiple of a plurality of visible resonant wavelengths,

wherein the display elements are formed such that the white light produced by the display elements is characterized by the standardized white point when illuminated by white light having a different white point.

60. The method of claim 59, wherein the light reflected by the display has a different white point than light illuminating the display.

61. The method of claim 59, wherein the standardized white point is a standard white point D55 associated with a color temperature of 5,500 ° K.

62. The method of claim 59, wherein the standardized white point is a standard white point D65 associated with a color temperature of 6,500 ° K.

63. The method of claim 59, wherein the standardized white point is a standard white point D75 associated with a color temperature of 7,500 ° K.

64. The apparatus of claim 59, wherein the plurality of visible resonant wavelengths includes one red resonant wavelength, one blue resonant wavelength, and one green resonant wavelength.

65. A display apparatus, comprising:

first means for selectively reflecting light having a first color;

second means for selectively reflecting light having a second color; and

third means for selectively reflecting light having a third color,

wherein the first, second and third means for reflecting light comprise first, second and third means for interferometrically modulating light, respectively, an

Wherein when illuminated by white light having a different white point, the reflected light of the first, second and third reflective members mixes to produce white light characterized by a normalized white point.

66. The apparatus of claim 65, further comprising means for adjusting the first, second, and third means, wherein the means for adjusting is configured to adjust the first, second, and third means to control a white point of generated white light for different visual environments.

67. The apparatus of claim 66, wherein each of the first, second, and third means comprises an area where light is reflected, and wherein the means for adjusting is configured to adjust the proportions of areas for reflecting the first, second, and third colors of light, respectively, to control the white point of the produced white light based on the visual environment.

68. The apparatus of claim 66, wherein the means for adjusting is configured to adjust their respective amounts of time when the first, second, and third means reflect light, thereby controlling a white point of the generated white light based on the visual environment.

69. The apparatus of claim 66, wherein said different visual environments comprise an office environment and a daylighting environment.

70. An apparatus as recited in claim 65, wherein said first, second and third means for outputting light comprises a plurality of display elements, each of said display elements comprising a reflective surface configured to be positioned at a distance from a portion of a reflective surface.

71. The apparatus of claim 65, further comprising means for selectively transmitting certain visible wavelengths and substantially filtering other visible wavelengths.

72. The apparatus according to claim 65, wherein said means for selectively transmitting comprises a filter.

73. The apparatus of claim 65, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

74. The apparatus of claim 65, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

75. The apparatus of claim 65, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

76. The apparatus of claim 65, further comprising illuminating means having a different white point than the white light produced by said first, second and third means for selectively reflecting light.

77. The apparatus of claim 65, wherein the first and second means for selectively reflecting light comprise first and second pixels, respectively.

78. The apparatus of any of claims 65, 70-77, wherein the first, second, and third means for outputting light comprise first, second, and third interferometric modulators, respectively.

79. A display apparatus, comprising:

means for reflecting light; and

means for partially reflecting the light of the light source,

wherein said reflecting means and said partially reflecting means comprise means for displaying an image, said displaying means comprises an interferometric modulator, and

wherein the display means is configured to output white light characterized by a standardized white point when illuminated by white light having a different white point.

80. The apparatus of claim 79, further comprising means for adjusting the means for reflecting light and the means for partially reflecting light, wherein the means for adjusting is configured to adjust the means for reflecting light and the means for partially reflecting light to control a white point of output white light for different visual environments.

81. The apparatus of claim 80, wherein each of the means for reflecting light and the means for partially reflecting light comprises an area where light is reflected, and wherein the means for adjusting is configured to adjust a proportion of areas for reflecting different colors of light to control a white point of the output white light based on the visual environment.

82. The apparatus of claim 80, wherein the means for adjusting is configured to adjust respective amounts of time when the means for reflecting light and the means for partially reflecting light reflect different colors of light to control a white point of the output white light based on the visual environment.

83. The apparatus of claim 80, wherein said different visual environments comprise an office environment and a daylighting environment.

84. An apparatus as recited in claim 79, wherein said partially reflecting means comprises a partially reflecting surface and said reflecting means comprises a reflecting surface.

85. The apparatus according to claim 79, wherein said display means comprises a plurality of display elements.

86. The apparatus of claim 85, wherein the plurality of display elements further comprises a plurality of display elements having different spectral outputs that together produce white light characterized by the standardized white point.

87. The apparatus of claim 85, wherein the plurality of display elements includes at least one display element configured to output red light, at least one display element configured to output green light, and at least one display element configured to output blue light, wherein the red light, the green light, and the blue light mix to produce the white output.

88. The apparatus of claim 85, further comprising a plurality of display elements having an area from which light is reflected, and wherein the respective areas of the display elements are selected to produce white light characterized by the standardized white point.

89. The apparatus of claim 85, wherein the plurality of display elements are configured to output white light.

90. The apparatus of claim 85, wherein the plurality of display elements are configured to output white light characterized by the standardized white point.

91. The apparatus of claim 85, wherein the reflecting means is configured to be positioned at a distance from the partially reflecting means to produce the white light characterized by the standardized white point.

92. The apparatus of claim 79, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

93. The apparatus of claim 79, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

94. The apparatus of claim 79, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

95. The apparatus of claim 79, further comprising means for illuminating the reflecting means and the partially reflecting means, the illuminating means outputting light having a different white point than the light reflected by the display.

96. The apparatus according to claim 95, wherein said illuminating means comprises an illumination source.

97. A display apparatus, comprising:

means for reflecting light; and

means for partially reflecting the light of the light source,

means for filtering light, the filtering means configured for selectively transmitting certain visible wavelengths and substantially filtering other visible wavelengths when illuminated with white light,

wherein the reflecting means and the partially reflecting means comprise means for displaying one image, the displaying means comprise interferometric modulators, and

wherein the display means is configured to output white light characterized by a standardized white point when illuminated by white light having a different white point.

98. The apparatus according to claim 97, wherein said display means comprises one display element.

99. The apparatus of claim 97, wherein the reflective surface is configured to be positioned at a distance from the partially reflective surface to generate the white light characterized by the standardized white point.

100. The apparatus of claim 97, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

101. The apparatus of claim 97, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

102. The apparatus of claim 97, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

103. The apparatus according to claim 97, wherein said filtering means comprises at least one filter.

104. The apparatus of claim 97, further comprising means for illuminating the reflecting means and the partially reflecting means, the illuminating means outputting light having a different white point than the light reflected by the display.

105. The apparatus according to claim 104, wherein said illumination means comprises an illumination source.

106. A display apparatus, comprising:

means for reflecting light; and

means for partially reflecting the light of the light source,

wherein said reflecting means and said partially reflecting means comprise means for displaying one image, said displaying means comprising interferometric modulators,

wherein the modulator has an optical path length between the reflective surface and the partially reflective surface selected to correspond to a common multiple of a plurality of visible resonant wavelengths, an

Wherein the display means is configured to output white light characterized by a standardized white point when illuminated by white light having a different white point.

107. The apparatus according to claim 106, wherein said display means comprises one display element.

108. The apparatus of claim 106, wherein the reflective surface is configured to be positioned at a distance from the partially reflective surface to generate the white light characterized by the normalized white point.

109. The apparatus of claim 106, wherein the standardized white point is a standardized white point D55 associated with a color temperature of 5,500 ° K.

110. The apparatus of claim 106, wherein the standardized white point is a standardized white point D65 associated with a color temperature of 6,500 ° K.

111. The apparatus of claim 106, wherein the standardized white point is a standardized white point D75 associated with a color temperature of 7,500 ° K.

112. The apparatus of claim 106, further comprising means for illuminating the reflecting means and the partially reflecting means, the illuminating means outputting light having a different white point than the light reflected by the display.

113. An apparatus as recited in claim 112, wherein said illumination means comprises an illumination source.

114. The apparatus of claim 106, wherein the plurality of visible resonant wavelengths includes one red resonant wavelength, one blue resonant wavelength, and one green resonant wavelength.