Patent Application
20130271437
This disclosure relates to a reflective display, and, more specifically, to improving the color performance of the reflective display by using environmental spectral sensing.
Electromechanical systems (EMS) include devices having electrical and mechanical elements, actuators, transducers, sensors, optical components (such as mirrors and optical film layers) and electronics. EMS can be manufactured at a variety of scales including, but not limited to, microscales and nanoscales. For example, microelectromechanical systems (MEMS) devices can include structures having sizes ranging from about a micron to hundreds of microns or more. Nanoelectromechanical systems (NEMS) devices can include structures having sizes smaller than a micron including, for example, sizes smaller than several hundred nanometers. Electromechanical elements may be created using deposition, etching, lithography, and/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 electromechanical systems device is called an interferometric modulator (IMOD). As used herein, the term IMOD or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In some implementations, an IMOD may include a pair of conductive plates, one or both of which may be transparent and/or reflective, wholly or in part, and capable of relative motion upon application of an appropriate electrical signal. In an implementation, one plate may include a stationary layer deposited on a substrate and the other plate may include a reflective membrane separated from the stationary layer by an air gap. The position of one plate in relation to another can change the optical interference of light incident on the IMOD. IMOD devices have a wide range of applications, and are anticipated to be used in improving existing products and creating new products, especially those with display capabilities, such as personal computers and personal electronic devices (PED's).
Electronic displays based on reflective elements (“reflective displays”) largely rely on reflection of ambient light to produce a visible image. Because the illumination source of a reflective display comes from its external environment, it consumes less power than, for example, a non-reflective display such as a conventional LCD or light emitting diode (LED) display. Thus, reflective displays may be advantageously employed in PED's. Moreover, reflective displays can provide readily visible images in bright ambient environments, including direct sunlight, where self-illuminated displays often provide a poor user experience.
Image quality of reflective displays, however, can be adversely affected when the spectral characteristics of the ambient light environment vary from a nominal characteristic. The presence or absence of particular hues in the ambient light illuminating the display can significantly alter the perceived color response of the display. In a color reflective display, for example, a display output color as perceived when the ambient light is incandescent, may be different from the output color perceived when the ambient light is fluorescent light, or direct or reflected sunlight. For example, an apparent hue of the image may be skewed noticeably toward the blue or red ends of the visible spectrum.
As a result, techniques for improving the color performance of reflective-displays by mitigating the adverse affects on image quality are desirable.
The systems, methods and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.
One innovative aspect of the subject matter described in this disclosure may be implemented in an electronic device having a reflective display, a spectrum sensing arrangement, and a display controller. The spectrum sensing arrangement may include a photodiode, a first portion of the photodiode being configured to generate a first signal, the first signal being responsive to an intensity of ambient visible light, and a second portion of the photodiode being configured to generate a second signal, the second signal being representative of an intensity of ambient infrared light. The display controller, in communication with the spectrum sensing arrangement, may be configured to make a comparison of the first signal and the second signal and control the display so as to dynamically adjust a color bias of the reflective display responsive to the comparison.
Another innovative aspect of the subject matter described in this disclosure may be implemented in an apparatus that includes a reflective display and a spectrum sensing arrangement. The spectrum sensing arrangement may include a photodiode, a first portion of the photodiode being configured to generate a first signal that is representative of an intensity of ambient visible light, and a second portion of the photodiode being configured to generate a second signal that is representative of an intensity of ambient infrared light. The apparatus also includes a display controller in communication with the spectrum sensing arrangement, the display controller configured to make a comparison of the first signal and the second signal, and dynamically adjust a color bias of the reflective display responsive to the comparison.
The comparison may indicate a relative intensity of ambient infrared light compared to ambient visible light. The display controller may be configured to adjust the color bias of the reflective display toward more blue when the relative intensity of ambient infrared light compared to ambient visible light is greater than a first threshold. The display controller may be configured to adjust the color bias of the reflective display toward more red when the relative intensity of ambient infrared light compared to ambient visible light is less than a second threshold.
The display controller may be configured to access a look-up table (LUT) and/or a formula that provides a target color bias corresponding to the comparison, and to dynamically adjust, responsive to the comparison, the color bias toward the target color bias.
The apparatus may further include an auxiliary light source. The display controller may be configured to dynamically adjust the color bias of the reflective display by adjusting one or both of an intensity and a color of the auxiliary light source. The auxiliary light source may include a front light.
The apparatus also may include a color processing engine. The reflective display may include a plurality of interferometric modulator (IMOD) devices. The color processing engine may provide bi-level or analog control of the IMOD devices. The display controller may be configured to dynamically adjust the color bias by adjusting an output of the color processing engine.
Another innovative aspect of the subject matter described in this disclosure may be implemented in an apparatus that includes a reflective display, a spectrum sensing arrangement; an auxiliary light source; and a display controller. The display controller may be in communication with the spectrum sensing arrangement and be configured to dynamically adjust a color bias of the reflective display by adjusting an intensity and/or a color of the auxiliary light source, responsive to a comparison of at least a first signal and a second signal from the spectrum sensing arrangement. The first signal may be indicative of an intensity of ambient visible light, and the second signal may be representative of an intensity of ambient infrared light.
The spectrum sensing arrangement may include a photodiode, a first portion of the photodiode being configured to generate the first signal, and a second portion of the photodiode configured to generate the second signal. The comparison may indicate a relative intensity of ambient infrared light compared to ambient visible light. The display controller may be configured to adjust the color bias of the reflective display toward more blue when the relative intensity of ambient infrared light compared to ambient visible light is greater than a first threshold, and to adjust the color bias of the reflective display toward more red when the relative intensity of ambient infrared light compared to ambient visible light is less than a second threshold. The auxiliary light source may include a front light.
Another innovative aspect of the subject matter described in this disclosure may be implemented in a portable electronic device (PED) including a reflective display, an ambient light sensor, an infrared (IR) proximity sensor; and a display controller. The display controller may be configured to dynamically adjust a color bias of the reflective display responsive to a comparison of at least a first signal from the ambient light sensor and a second signal from the IR proximity sensor.
The PED may further include an auxiliary light source, and the display controller may be configured to dynamically adjust the color bias of the reflective display by adjusting an intensity and/or a color of the front light.
Another innovative aspect of the subject matter described in this disclosure may be implemented in a method, the method that involves receiving, at a display controller, a first signal and a second signal output by a spectrum sensing arrangement including a photodiode, where a first portion of the photodiode is configured to generate a first signal representative of an intensity of ambient visible light, and a second portion of the photodiode is configured to generate a second signal representative of an intensity of ambient infrared light. The method further involves the display controller making a comparison of the first signal and the second signal and dynamically adjusting a color bias of a reflective display responsive to the comparison.
Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Although the examples provided in this summary are primarily described in terms of MEMS-based displays, the concepts provided herein apply to other types of displays, such as organic light-emitting diode (“OLED”) displays and field emission displays. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.
Like reference numbers and designations in the various drawings indicate like elements.
The following description is directed to certain implementations for the purposes of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations may be implemented in any device or system that can be configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual, graphical or pictorial. More particularly, it is contemplated that the described implementations may be included in or associated with a variety of electronic devices such as, but not limited to: mobile telephones, multimedia Internet enabled cellular telephones, mobile television receivers, wireless devices, smartphones, Bluetooth® devices, personal data assistants (PDAs), wireless electronic mail receivers, hand-held or portable computers, netbooks, notebooks, smartbooks, tablets, printers, copiers, scanners, facsimile devices, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (i.e., e-readers), computer monitors, auto displays (including odometer and speedometer displays, etc.), cockpit controls and/or displays, camera view displays (such as the display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer/dryers, parking meters, packaging (such as in electromechanical systems (EMS), microelectromechanical systems (MEMS) and non-MEMS applications), aesthetic structures (e.g., display of images on a piece of jewelry) and a variety of EMS devices. The teachings herein also can be used in non-display applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion-sensing devices, magnetometers, inertial components for consumer electronics, parts of consumer electronics products, varactors, liquid crystal devices, electrophoretic devices, drive schemes, manufacturing processes and electronic test equipment. Thus, the teachings are not intended to be limited to the implementations depicted solely in the Figures, but instead have wide applicability as will be readily apparent to one having ordinary skill in the art.
Described herein below are new techniques incorporating, in an electronic device having a reflective display, a spectrum sensing arrangement and a display controller. The spectrum sensing arrangement may include a photodiode, a first portion of the photodiode being configured to generate a first signal, the first signal being responsive to an intensity of ambient visible light, and a second portion of the photodiode being configured to generate a second signal, the second signal being representative of an intensity of ambient infrared light. The display controller, in communication with the spectrum sensing arrangement, may be configured to make a comparison of the first signal and the second signal and control the display so as to dynamically adjust a color bias of the reflective display responsive to the comparison. In some implementations, the display controller may be configured to adjust the color bias, at least in part, based on either or both of content being displayed and viewer preferences.
Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. The image quality of a reflective display of an electronic device can be substantially improved in the face of changing ambient light conditions by dynamically adjusting a color bias of the display, responsive to signals received from a spectrum sensing arrangement. The spectrum sensing arrangement itself may be relatively simple, and consist of off the shelf components. In some implementations, the spectrum sensing arrangement may largely or entirely consist of electronic devices that are already, for other reasons, incorporated in the electronic device. For example, signals output by an ambient light sensor (ALS) and an infrared (IR) proximity sensor (devices which are routinely incorporated in some types of electronic devices) may be used as inputs to a display controller. The display controller can make a comparison of the signals output by the spectrum sensing arrangement and control the display so as to dynamically adjust a color bias of the reflective display responsive to the comparison. As a result, adverse effects on display output color quality caused by changing ambient light conditions may be minimized or eliminated, without substantially increasing the cost or complexity of the electronic device.
Moreover, in certain lighting conditions (such as near-monochromatic conditions including, for example, outdoor sodium vapor lighting and darkroom illumination) operating a display in high-contrast mode may be contemplated. In such a high contrast mode, in some implementations, only a specific subset of color elements may be used. For example, in a red-only environment IMODs ordinarily configured to modulate green and blue light may be disabled. As a result, display power consumption may be reduced with no loss of image clarity because such IMODs would not be operable to modulate red light.
As a further example the display may be operated in a high-resolution, monochromatic, mode, responsive to ambient lighting conditions. In such a mode, all IMODs may be configured to modulate light of a particular wavelength, responsive to a detected narrow band ambient light environment and a high-resolution monochrome image may be produced. For example, original image data may be sub-sampled to individually address each IMOD in the display. In a dark or nearly dark environment, an artificial narrow band light input to the display may be provided by a supplemental illumination from a front light. The front light, for example may be configured to provide a narrow band spectrum (for example, from a red or RGB LED). There are potential industrial and some military applications of such an adaptable display behavior.
Although much of the description herein pertains to IMOD displays, many such implementations could be used to advantage in other types of reflective displays, including but not limited to electrophoretic ink displays and displays based on electrowetting technology. Moreover, while the IMOD displays described herein generally include red, blue and green pixels, many implementations described herein could be used in reflective displays having other colors of pixels, such as having violet, yellow-orange and yellow-green pixels. Moreover, many implementations described herein could be used in reflective displays having more colors of pixels, such as having pixels corresponding to 4, 5, or more colors. Some such implementations may include pixels corresponding to red, blue, green and yellow. Alternative implementations may include pixels corresponding to at least red, blue, green, yellow and cyan.
An example of a suitable device, to which the described implementations may apply, is a reflective EMS or MEMS-based display device. Reflective display devices can incorporate interferometric modulators (IMODs) to selectively absorb and/or reflect light incident thereon using principles of optical interference. IMODs can include an absorber, a reflector that is movable with respect to the absorber, and an optical resonant cavity defined between the absorber and the reflector. The reflector can be moved to two or more different positions, which can change the size of the optical resonant cavity and thereby affect the reflectance of the IMOD. The reflectance spectrums of IMODs can create fairly broad spectral bands which can be shifted across the visible wavelengths to generate different colors. The position of the spectral band can be adjusted by changing the thickness of the optical resonant cavity. One way of changing the optical resonant cavity is by changing the position of the reflector.
The IMOD display device can include a row/column array of IMODs. Each IMOD can include a pair of reflective layers, i.e., a movable reflective layer and a fixed partially reflective layer, positioned at a variable and controllable distance from each other to form an air gap (also referred to as an optical gap or cavity). The movable reflective layer may be moved between at least two positions. In a first position, i.e., a relaxed position, the movable reflective layer can be positioned at a relatively large distance from the fixed partially reflective layer. In a second position, i.e., an actuated position, the movable reflective layer can be positioned more closely to the partially reflective layer. Incident light that reflects from the two layers can interfere constructively or destructively depending on the position of the movable reflective layer, producing either an overall reflective or non-reflective state for each pixel. In some implementations, the IMOD may be in a reflective state when unactuated, reflecting light within the visible spectrum, and may be in a dark state when unactuated, absorbing and/or destructively interfering light within the visible range. In some other implementations, however, an IMOD may be in a dark state when unactuated, and in a reflective state when actuated. In some implementations, the introduction of an applied voltage can drive the pixels to change states. In some other implementations, an applied charge can drive the pixels to change states.
The depicted portion of the pixel array in
In
The optical stack 16 can include a single layer or several layers. The layer(s) can include one or more of an electrode layer, a partially reflective and partially transmissive layer and a transparent dielectric layer. In some implementations, the optical stack 16 is electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more of the above layers onto a transparent substrate 20. The electrode layer can be formed from a variety of materials, such as various metals, for example indium tin oxide (ITO). The partially reflective layer can be formed from a variety of materials that are partially reflective, such as various metals, such as chromium (Cr), semiconductors, and dielectrics. The partially reflective layer can be formed of one or more layers of materials, and each of the layers can be formed of a single material or a combination of materials. In some implementations, the optical stack 16 can include a single semi-transparent thickness of metal or semiconductor which serves as both an optical absorber and electrical conductor, while different, electrically more conductive layers or portions (e.g., of the optical stack 16 or of other structures of the IMOD) can serve to bus signals between IMOD pixels. The optical stack 16 also can include one or more insulating or dielectric layers covering one or more conductive layers or an electrically conductive/optically absorptive layer.
In some implementations, the layer(s) of the optical stack 16 can be patterned into parallel strips, and may form row electrodes in a display device as described further below. As will be understood by one having ordinary skill in the art, the term “patterned” is used herein to refer to masking as well as etching processes. In some implementations, a highly conductive and reflective material, such as aluminum (Al), may be used for the movable reflective layer 14, and these strips may form column electrodes in a display device. The movable reflective layer 14 may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes of the optical stack 16) to form columns deposited on top of posts 18 and an intervening sacrificial material deposited between the posts 18. When the sacrificial material is etched away, a defined gap 19, or optical cavity, can be formed between the movable reflective layer 14 and the optical stack 16. In some implementations, the spacing between posts 18 may be approximately 1-1000 um, while the gap 19 may be approximately less than 10,000 Angstroms (Å).
In some implementations, each pixel of the IMOD, whether in the actuated or relaxed state, is essentially a capacitor formed by the fixed and moving reflective layers. When no voltage is applied, the movable reflective layer 14 remains in a mechanically relaxed state, as illustrated by the pixel 12 on the left in
The processor 21 can be configured to communicate with an array driver 22. The array driver 22 can include a row driver circuit 24 and a column driver circuit 26 that provide signals to, for example, a display array or panel 30. The cross section of the IMOD display device illustrated in
In some implementations, a frame of an image may be created by applying data signals in the form of “segment” voltages along the set of column electrodes, in accordance with the desired change (if any) to the state of the pixels in a given row. Each row of the array can be addressed in turn, such that the frame is written one row at a time. To write the desired data to the pixels in a first row, segment voltages corresponding to the desired state of the pixels in the first row can be applied on the column electrodes, and a first row pulse in the form of a specific “common” voltage or signal can be applied to the first row electrode. The set of segment voltages can then be changed to correspond to the desired change (if any) to the state of the pixels in the second row, and a second common voltage can be applied to the second row electrode. In some implementations, the pixels in the first row are unaffected by the change in the segment voltages applied along the column electrodes, and remain in the state they were set to during the first common voltage row pulse. This process may be repeated for the entire series of rows, or alternatively, columns, in a sequential fashion to produce the image frame. The frames can be refreshed and/or updated with new image data by continually repeating this process at some desired number of frames per second.
The combination of segment and common signals applied across each pixel (that is, the potential difference across each pixel) determines the resulting state of each pixel.
As illustrated in
When a hold voltage is applied on a common line, such as a high hold voltage VCHOLD
When an addressing, or actuation, voltage is applied on a common line, such as a high addressing voltage VCADD
In some implementations, hold voltages, address voltages, and segment voltages may be used which produce the same polarity potential difference across the modulators. In some other implementations, signals can be used which alternate the polarity of the potential difference of the modulators from time to time. Alternation of the polarity across the modulators (that is, alternation of the polarity of write procedures) may reduce or inhibit charge accumulation which could occur after repeated write operations of a single polarity.
During the first line time 60a: a release voltage 70 is applied on common line 1; the voltage applied on common line 2 begins at a high hold voltage 72 and moves to a release voltage 70; and a low hold voltage 76 is applied along common line 3. Thus, the modulators (common 1, segment 1), (1,2) and (1,3) along common line 1 remain in a relaxed, or unactuated, state for the duration of the first line time 60a, the modulators (2,1), (2,2) and (2,3) along common line 2 will move to a relaxed state, and the modulators (3,1), (3,2) and (3,3) along common line 3 will remain in their previous state. With reference to
During the second line time 60b, the voltage on common line 1 moves to a high hold voltage 72, and all modulators along common line 1 remain in a relaxed state regardless of the segment voltage applied because no addressing, or actuation, voltage was applied on the common line 1. The modulators along common line 2 remain in a relaxed state due to the application of the release voltage 70, and the modulators (3,1), (3,2) and (3,3) along common line 3 will relax when the voltage along common line 3 moves to a release voltage 70.
During the third line time 60c, common line 1 is addressed by applying a high address voltage 74 on common line 1. Because a low segment voltage 64 is applied along segment lines 1 and 2 during the application of this address voltage, the pixel voltage across modulators (1,1) and (1,2) is greater than the high end of the positive stability window (i.e., the voltage differential exceeded a predefined threshold) of the modulators, and the modulators (1,1) and (1,2) are actuated. Conversely, because a high segment voltage 62 is applied along segment line 3, the pixel voltage across modulator (1,3) is less than that of modulators (1,1) and (1,2), and remains within the positive stability window of the modulator; modulator (1,3) thus remains relaxed. Also during line time 60c, the voltage along common line 2 decreases to a low hold voltage 76, and the voltage along common line 3 remains at a release voltage 70, leaving the modulators along common lines 2 and 3 in a relaxed position.
During the fourth line time 60d, the voltage on common line 1 returns to a high hold voltage 72, leaving the modulators along common line 1 in their respective addressed states. The voltage on common line 2 is decreased to a low address voltage 78. Because a high segment voltage 62 is applied along segment line 2, the pixel voltage across modulator (2,2) is below the lower end of the negative stability window of the modulator, causing the modulator (2,2) to actuate. Conversely, because a low segment voltage 64 is applied along segment lines 1 and 3, the modulators (2,1) and (2,3) remain in a relaxed position. The voltage on common line 3 increases to a high hold voltage 72, leaving the modulators along common line 3 in a relaxed state.
Finally, during the fifth line time 60e, the voltage on common line 1 remains at high hold voltage 72, and the voltage on common line 2 remains at a low hold voltage 76, leaving the modulators along common lines 1 and 2 in their respective addressed states. The voltage on common line 3 increases to a high address voltage 74 to address the modulators along common line 3. As a low segment voltage 64 is applied on segment lines 2 and 3, the modulators (3,2) and (3,3) actuate, while the high segment voltage 62 applied along segment line 1 causes modulator (3,1) to remain in a relaxed position. Thus, at the end of the fifth line time 60e, the 3×3 pixel array is in the state shown in
In the timing diagram of
The details of the structure of IMODs that operate in accordance with the principles set forth above may vary widely. For example,
As illustrated in
In implementations such as those shown in
The process 80 continues at block 84 with the formation of a sacrificial layer 25 over the optical stack 16. The sacrificial layer 25 is later removed (see block 90) to form the cavity 19 and thus the sacrificial layer 25 is not shown in the resulting IMODs 12 illustrated in
The process 80 continues at block 86 with the formation of a support structure such as post 18, illustrated in
The process 80 continues at block 88 with the formation of a movable reflective layer or membrane such as the movable reflective layer 14 illustrated in
The process 80 continues at block 90 with the formation of a cavity, such as cavity 19 illustrated in
As described in more detail herein below, the spectrum sensing arrangement 930, in some implementations, may include a photo diode, a first portion of which is configured to generate the first signal 931, and a second portion of which is configured to generate the second signal 932. In some implementations, a single photodiode device may be so configured by placement of one or more appropriate thin film filter(s) over at least part of a sensing portion of the photodiode device.
Additional features of this disclosure may be better appreciated by referring first to
As noted above, the output color characteristics of a reflective display can be significantly affected by spectrum bias of ambient light, such as the above noted blue-shift of solar ambient light and red-shift of halogen and incandescent light. Nevertheless, reflective display controllers are generally designed to cause a display to output colors based on a single assumed ambient spectrum. For example, Standard Illuminant D65, defined by the International Commission on Illumination (CIE), and illustrated in
Users of electronic devices, however, desire that color output of a display be of uniformly good quality, irrespective of the ambient light conditions, and irrespective of dynamic changes in the ambient light conditions. For example, when the user takes a portable electronic device (PED) from an outdoor environment to an indoor environment, or from an environment illuminated by incandescent lights to one illuminated by fluorescent lights, the user does not expect to perceive changes in the color output of the PED's display.
The above noted user expectation may be met, advantageously, by configuring a display controller to exploit information about the ambient light characteristics that is already collected for other purposes by devices commonly implemented on electronic devices. For example, most modern PEDs include one or more photo detecting elements for detecting characteristics of ambient light, such as an ambient light sensor (ALS) and an IR/proximity sensor. An ALS may be used, for example, to increase or decrease the brightness of a display based on a detected general intensity of ambient visible light. An IR/proximity sensor may be used to detect the proximity of a person or object.
Thus, in some implementations, the spectrum sensing arrangement 930 depicted in
Whether or not spectrum sensing arrangement 930 includes an existing ALS and an existing IR proximity sensor, the display controller 940 may be configured to make a comparison of the first signal 931 and the second signal 932 from the spectrum sensing arrangement 930. In some implementations, the comparison may indicate a relative intensity of ambient infrared light compared to ambient visible light.
The display controller 940 may be further configured to adjust the color bias of the reflective display 910 toward more blue when the relative intensity of ambient infrared light compared to ambient visible light is high and to adjust the color bias of the reflective display 910 toward more red when the relative intensity of ambient infrared light compared to ambient visible light is low. In some implementations, when the relative intensity of ambient infrared light compared to ambient visible light is greater than a first threshold the color bias of reflective display 910 may be adjusted toward more blue. When the relative intensity of ambient infrared light compared to ambient visible light is less than a second threshold the color bias of reflective display 910 may be adjusted toward more red. The first threshold and the second threshold may be preset, or determined dynamically, either by display controller 940 or the user.
It will be appreciated that display controller 940 may be configured to process first signal 931 and second signal 932 in various ways in order to make a comparison indicative of a relative intensity of ambient infrared light compared to ambient visible light. For example, a difference and/or a ratio of first signal 931 and second signal 932 may be computed, with or without first normalizing the respective signals. As a further example, each of first signal 931 and second signal 932 may be compared to a standard, for example to CIE D65.
In some implementations, electronic device 900 may include a color processing engine (not illustrated) and reflective display 910 may include a number of IMOD devices (not illustrated). The color processing engine may provide bi-level or analog control of the IMOD devices. In such implementations, the display controller 940 may be configured to dynamically adjust the color bias of the reflective display 910 by adjusting an output of the color processing engine. The color processing engine may be implemented within the display controller 940, or be a separate device (for example, an application specific integrated circuit) or a software module stored on a non-transitory medium.
In some implementations, the display controller 940 may be configured to access a lookup table (LUT) and/or a formula that provides a target color bias corresponding to the comparison. The display controller 940 may dynamically adjust the color bias of reflective display 910 toward the target color bias.
In some implementations, the LUT and/or the formula may be based, at least in part, on an illumination model that is based at least in part on the content (e.g., text, image, or video) being displayed. Content may not significantly influence the target color bias, but it may be desired to have a different color bias for textual content as compared, for example, to video and/or photographic content, at least for some viewers. Thus, in some implementations, the display controller 940 may be configured to determine the amount of supplemental light based at least in part on the content being displayed. For example, when a photographic image is being displayed, the display controller 940 may determine the target color bias based at least in part on an illumination model that takes into account the content of an image being displayed.
In some implementations, the illumination model may have default parameters which may be adjusted based on viewer preferences. For example, the default parameters may be based on average preferences of a majority of viewers. To accommodate for differences in viewer preferences, some implementations of the electronic device 900 further may include a user interface with which a viewer can adjust default parameters.
In addition, certain implementations of electronic device 900 may store (such as on a memory device in communication with display controller 940) the viewer adjusted preference for an ambient lighting condition. The viewer preference for the lighting condition may be used to adjust the default parameters to provide a viewer illumination model. Upon use of the electronic device 900 in a different or same ambient lighting condition, certain implementations may update the viewer preference model. Thus, in these implementations, the display controller 940 may be configured to optionally access the viewer preference model. In addition, in some implementations, the display controller 940 may override a default illumination model and adjust the color bias of the reflective display 910 in conformance with the viewer preference model.
The spectral sensing arrangement 930 may be configured to determine spectral characteristics of ambient light illuminating the reflective display 910. The display controller 940 may be configured, responsive to the first signal 931 and the second signal 932 from the spectrum sensing arrangement 930, to dynamically adjust a color bias of the reflective display 910 by adjusting an intensity and/or a color of the auxiliary light source 1320.
In an implementation, the first signal 931 may be representative of an intensity level of visible ambient light while the second signal 932 may be representative of an intensity level of infrared (IR) ambient light. The display controller 940 may be configured to make a comparison of the first signal 931 and the second signal 932. Based on the comparison, an intensity and/or color of supplemental light from the auxiliary light source 1320 may be dynamically adjusted.
In addition, where the electronic device 1300 includes a color processing engine and the reflective display 910 includes a number of IMOD devices, the color processing engine may provide bi-level or analog control of the IMOD devices. In such implementations, the display controller 940 may be configured to dynamically adjust the color bias of the reflective display 910 by adjusting an output of the color processing engine.
In addition, or alternatively, where the electronic device 1400 includes a color processing engine and the reflective display 910 includes a number of IMOD devices, the color processing engine may provide bi-level or analog control of the IMOD devices. In such implementations, the display controller 940 may be configured to dynamically adjust the color bias of the reflective display 910 by adjusting an output of the color processing engine.
It will be appreciated that the display controller 940 may be configured to process respective signals from the visible light sensor 1431 and the IR light sensor 1432 in various ways in order to make a comparison indicative of a relative intensity of ambient infrared light compared to ambient visible light. For example, a difference and/or a ratio of respective signals from the visible light sensor 1431 and the IR light sensor 1432 may be computed, with or without first normalizing the respective signals. As a further example, each respective signal may be compared to a standard, for example to CIE D65.
It will be understood that the visible light sensor 1431 and the IR light sensor 1432 may be separate components or may be monolithically integrated onto the same semiconductor substrate. Moreover, the visible light sensor 1431 and the IR light sensor 1432 may be disposed in a thin-film semiconducting film (for example, amorphous silicon, geranium indium gallium arsenide and/or lead sulfide). Similarly, the spectral sensing arrangement 930 may include one or more photodiodes, integrated onto the same semiconductor substrate or may be disposed in a thin-film semiconducting film.
Referring now to
The shape of the display 1710 may be, as illustrated, substantially rectangular, but other shapes, such as square or oval also may be used. The display 1710 may be made of glass, plastic, or other material. The display 1710 may include a reflective display, such as displays including reflective IMODs as discussed herein. In some other implementations, the display 1710 may include a transflective display.
The PED 1700 may include an auxiliary light source 1720 configured to provide supplemental light to the display 1710. In some implementations, the auxiliary light source 1720 may include a front-light, e.g., for a reflective display. In some other implementations, the auxiliary light source 1720 may include a back-light, e.g., for a transflective display. The auxiliary light source 1720 may be any type of light source(s), e.g., one or more white or color light emitting diodes (LED). In some implementations, a light guide (not shown) may be used to receive light from the auxiliary light source 1720 and guide the light to one or more portions of the display 1710.
At block 1820, a comparison may be made of the first signal and the second signal to determine whether the comparison indicates that the relative intensity of ambient infrared compared to ambient visible light is greater than a first threshold. Advantageously, the first threshold may be set to such a value that differences in the relative intensities of ambient infrared light compared to ambient visible light that are significant enough to effect a user's perception of display quality, result in a determination to adjust a color bias of the display.
The first threshold may be predefined and/or fixed; however in some implementations, the threshold may be adjustable based on other ambient conditions (such as general levels of ambient conditions such as natural daylight, dark, indoor or outdoor artificial illumination, and/or rate of change of those ambient conditions), user preferences, and/or content of image to be displayed. If at block 1820, a determination is made that the relative intensity of ambient infrared compared to ambient visible light is not greater than the first threshold, the method may proceed to block 1840.
On the other hand, if a determination is made that the relative intensity of ambient infrared compared to ambient visible light is greater than the first threshold, the method may proceed to block 1830. At block 1830, a color bias of the reflective display is adjusted toward more blue. In some implementations, the color bias may be adjusted by adjusting, with the display controller, one or both of an intensity and a color of an auxiliary light source, such as, for example, a front light of the reflective display. In another implementation, the color bias may be adjusted by adjusting, with the display controller, an output of a color processing engine that provides bi-level or analog control of IMOD devices incorporated in the reflective display.
Following adjustment of the color bias at block 1830, the method may return to block 1810, either immediately, or after an interval of time.
If at block 1820 the determination is made that the relative intensity of ambient infrared compared to ambient visible light is not greater than the first threshold, the method may proceed to block 1840. At block 1840, a comparison may be made of the first signal and the second signal to determine whether the comparison indicates that the relative intensity of ambient infrared compared to ambient visible light is less than a second threshold. In some implementations, the second threshold may be set to such a value that differences in the relative intensities of ambient infrared light compared to ambient visible light that are significant enough to effect a user's perception of display quality, result in a determination to adjust a color bias of the display.
The second threshold may be predefined and/or fixed; however in some implementations, the second threshold may be adjustable based on other ambient conditions (such as general levels of ambient conditions such as natural daylight, dark, indoor or outdoor artificial illumination, and/or rate of change of those ambient conditions), user preferences, and/or content of image to be displayed. If at block 1840, a determination is made that the relative intensity of ambient infrared compared to ambient visible light is not less than the first threshold, the method may return to block 1810, either immediately, or after an interval of time.
On the other hand, if at block 1840 a determination is made that the relative intensity of ambient infrared light compared to ambient visible light is less than the second threshold, the method may proceed to block 1850. At block 1850, a color bias of the reflective display may be adjusted toward more red. In some implementations, the color bias may be adjusted by adjusting, with the display controller, one or both of an intensity and a color of an auxiliary light source, such as, for example, a front light of the reflective display. In another implementation, the color bias may be adjusted by adjusting, with the display controller, an output of a color processing engine that provides bi-level or analog control of IMOD devices incorporated in the reflective display.
Following adjustment of the color bias at block 1850, the method may return to block 1810, either immediately, or after an interval of time.
At block 1920, a comparison of the first signal and the second signal may be made by, for example a display controller. The comparison may indicate a relative intensity of ambient infrared light compared to ambient visible light.
At block 1930, a color bias of the reflective display may be dynamically adjusted, responsive to the comparison. The dynamic adjustment may be performed in accordance with method 1800 described herein above. As a result, a color bias of the reflective display is adjusted so as to prevent degradation of image quality that would otherwise occur as a result of changing spectral characteristics of ambient light.
The display device 40 includes a housing 41, a display 30, an antenna 43, a speaker 45, an input device 48 and a microphone 46. The housing 41 can be formed from any of a variety of manufacturing processes, including injection molding, and vacuum forming. In addition, the housing 41 may be made from any of a variety of materials, including, but not limited to: plastic, metal, glass, rubber and ceramic, or a combination thereof. The housing 41 can include removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols.
The display 30 may be any of a variety of displays, including a bi-stable or analog display, as described herein. The display 30 also can be configured to include a flat-panel display, such as plasma, EL, OLED, STN LCD, or TFT LCD, or a non-flat-panel display, such as a CRT or other tube device. In addition, the display 30 can include an IMOD display, as described herein.
The components of the display device 40 are schematically illustrated in
The network interface 27 includes the antenna 43 and the transceiver 47 so that the display device 40 can communicate with one or more devices over a network. The network interface 27 also may have some processing capabilities to relieve, for example, data processing requirements of the processor 21. The antenna 43 can transmit and receive signals. In some implementations, the antenna 43 transmits and receives RF signals according to the IEEE 16.11 standard, including IEEE 16.11(a), (b), or (g), or the IEEE 802.11 standard, including IEEE 802.11a, b, g, n, and further implementations thereof. In some other implementations, the antenna 43 transmits and receives RF signals according to the BLUETOOTH standard. In the case of a cellular telephone, the antenna 43 is designed to receive code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals that are used to communicate within a wireless network, such as a system utilizing 3G or 4G technology. The transceiver 47 can pre-process the signals received from the antenna 43 so that they may be received by and further manipulated by the processor 21. The transceiver 47 also can process signals received from the processor 21 so that they may be transmitted from the display device 40 via the antenna 43.
In some implementations, the transceiver 47 can be replaced by a receiver. In addition, in some implementations, the network interface 27 can be replaced by an image source, which can store or generate image data to be sent to the processor 21. The processor 21 can control the overall operation of the display device 40. The processor 21 receives data, such as compressed image data from the network interface 27 or an image source, and processes the data into raw image data or into a format that is readily processed into raw image data. The processor 21 can send the processed data to the driver controller 29 or to the frame buffer 28 for storage. Raw data typically refers to the information that identifies the image characteristics at each location within an image. For example, such image characteristics can include color, saturation and gray-scale level.
The processor 21 can include a microcontroller, CPU, or logic unit to control operation of the display device 40. The conditioning hardware 52 may include amplifiers and filters for transmitting signals to the speaker 45, and for receiving signals from the microphone 46. The conditioning hardware 52 may be discrete components within the display device 40, or may be incorporated within the processor 21 or other components.
The driver controller 29 can take the raw image data generated by the processor 21 either directly from the processor 21 or from the frame buffer 28 and can re-format the raw image data appropriately for high speed transmission to the array driver 22. In some implementations, the driver controller 29 can re-format 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 30. Then the driver controller 29 sends the formatted information to the array driver 22. Although a driver controller 29, such as an LCD controller, is often associated with the system processor 21 as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. For example, controllers may be embedded in the processor 21 as hardware, embedded in the processor 21 as software, or fully integrated in hardware with the array driver 22.
The array driver 22 can receive the formatted information from the driver controller 29 and can re-format the video data into a parallel set of waveforms that are applied many times per second to the hundreds, and sometimes thousands (or more), of leads coming from the display's x-y matrix of pixels.
In some implementations, the driver controller 29, the array driver 22, and the display array 30 are appropriate for any of the types of displays described herein. For example, the driver controller 29 can be a conventional display controller or a bi-stable display controller (such as an IMOD controller). Additionally, the array driver 22 can be a conventional driver or a bi-stable display driver (such as an IMOD display driver). Moreover, the display array 30 can be a conventional display array or a bi-stable display array (such as a display including an array of IMODs). In some implementations, the driver controller 29 can be integrated with the array driver 22. Such an implementation can be useful in highly integrated systems, for example, mobile phones, portable-electronic devices, watches or small-area displays.
In some implementations, the input device 48 can be configured to allow, for example, a user to control the operation of the display device 40. The input device 48 can include a keypad, such as a QWERTY keyboard or a telephone keypad, a button, a switch, a rocker, a touch-sensitive screen, or a pressure- or heat-sensitive membrane. The microphone 46 can be configured as an input device for the display device 40. In some implementations, voice commands through the microphone 46 can be used for controlling operations of the display device 40.
The power supply 50 can include a variety of energy storage devices. For example, the power supply 50 can be a rechargeable battery, such as a nickel-cadmium battery or a lithium-ion battery. In implementations using a rechargeable battery, the rechargeable battery may be chargeable using power coming from, for example, a wall socket or a photovoltaic device or array. Alternatively, the rechargeable battery can be wirelessly chargeable. The power supply 50 also can be a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell or solar-cell paint. The power supply 50 also can be configured to receive power from a wall outlet.
In some implementations, control programmability resides in the driver controller 29 which can be located in several places in the electronic display system. In some other implementations, control programmability resides in the array driver 22. The above-described optimization may be implemented in any number of hardware and/or software components and in various configurations.
The various illustrative logics, logical blocks, modules, circuits and algorithm steps described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and steps described above. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.
The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular steps and methods may be performed by circuitry that is specific to a given function.
In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Implementations of the subject matter described in this specification also can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on a computer storage media for execution by, or to control the operation of, data processing apparatus.
If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The steps of a method or algorithm disclosed herein may be implemented in a processor-executable software module which may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program from one place to another. A storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection can be properly termed a computer-readable medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above also may be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine readable medium and computer-readable medium, which may be incorporated into a computer program product.
Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other possibilities or implementations. Additionally, a person having ordinary skill in the art will readily appreciate, the terms “upper” and “lower” are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of an IMOD as implemented.
Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, a person having ordinary skill in the art will readily recognize that such operations need not be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.
