The present disclosure relates generally to display devices, and more particularly, to techniques for controlling surface reflection on display devices.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Display technology may be used in a wide variety of electronic devices, including such consumer electronics as televisions, computers, and handheld devices (e.g., cellular telephones, audio and video players, gaming systems, and so forth). Such display devices typically provide a flat display in a relatively thin package that is suitable for use in a variety of electronic goods. In addition, touch-screen capabilities have become increasingly popular in such display devices. Such touch-screen capabilities enable a user to perform various functions by touching the display surface using a finger or other object at a location displayed on the display device.
A display device typically includes multiple layers, including a pixel matrix configured to selectively modulate the amount and color of light transmitted or emitted. Display devices having touch-screen capabilities also typically have a touch-screen panel including an arrangement of electrodes made of conductive materials. However, in some configurations of display devices, external light may be reflected from the touch-screen panel, resulting in undesirable light reflections from the display surface.
A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.
Techniques are provided for reducing reflections from display devices with touch capabilities. Typically, in display devices having touch-screen capabilities includes a touch-screen panel configured over a display panel. Examples of the display panel include liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays. However, the touch-screen panel may contribute to undesirable light reflections. For instance, external light may pass through the top surface of the display device and be reflected from the touch-screen panel. In particular, the touch-screen panel may include an arrangement of conductive electrodes which significantly reflect external light. Undesirable reflections of external light may be perceived as glare and/or undesirable patterns and may reduce the visibility of the images displayed by the display device, particularly in bright ambient light environments. In some embodiments, a circular polarizer is positioned above the touch-screen panel (i.e., over the electrodes). A circular polarizer may include a linear polarizer and a quarter-wave (λ/4) plate. The circular polarizer may absorb a significant amount of the reflections from the touch-screen panel, particularly the reflections from the electrodes, thereby reducing undesirable light reflections from the touch-screen panel.
Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:
One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
Certain embodiments of the present disclosure are generally directed towards reducing surface reflections on a display device. In display devices having touch-screen capabilities, a touch-screen panel is typically configured over the display panel. The touch-screen panel generally includes an arrangement of conductive electrodes. However, external light (e.g., ambient light, such as sunlight or artificial light) may be reflected from the touch-screen panel, and in particular, the electrodes of the touch-screen panel. Such undesirable light reflections may be perceived as glare and/or undesirable patterns on the display screen and may reduce the visibility of the displayed images, particularly in bright ambient light environments, such as the outdoors. More specifically, due to such undesirable light reflections, the electrodes may be visibly perceptible to a user.
In some embodiments, a display device includes a circular polarizer positioned above the touch-screen panel (i.e., over the electrodes of the touch-screen panel). In one of more embodiments, the circular polarizer includes a linear polarizer positioned over a quarter-wave plate. When external light travels toward the touch-screen panel of the display device, the light is first transmitted through the circular polarizer where it is polarized by the linear polarizer and phase-shifted by a quarter of its wavelength by the quarter-wave plate. The light is then reflected by a reflective surface, such as a touch electrode or other reflective portion of the touch-screen panel. As the reflected light travels away from the touch-screen panel, it is again phase shifted by the quarter-wave plate and absorbed by the linear polarizer of the circular polarizer. Therefore, by configuring a circular polarizer between the touch-screen panel and potential propagations of unpolarized light, reflections of unpolarized light from the touch-display device surface of the display device may be substantially decreased. With these foregoing features in mind, a general description of electronic devices including a display that may use the presently disclosed technique is provided below.
As may be appreciated, electronic devices may include various internal and/or external components which contribute to the function of the device. For instance,
The display 12 may be used to display various images generated by the electronic device 10. The display 12 may be any suitable display, such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display. Additionally, in certain embodiments of the electronic device 10, the display 12 may be provided in conjunction with a touch-sensitive element, such as a touch-screen, that may be used as part of the control interface for the device 10. For example, a touch-screen capable display 12 may include a touch-screen panel having an arrangement of electrodes. The display 12 may include a matrix of pixels and circuitry for modulating the transmittance of light through each pixel to display an image.
The electronic device 10 may take the form of a computer system or some other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, tablet, and handheld computers), as well as computers that are generally used in one place (such as conventional desktop computers, workstations and/or servers). In certain embodiments, electronic device 10 in the form of a computer may include a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, Calif. By way of example, an electronic device 10 in the form of a laptop computer 30 is illustrated in
The display 12 may be integrated with the computer 30 (e.g., such as the display of the depicted laptop computer) or may be a standalone display that interfaces with the computer 30 using one of the I/O ports 14, such as via a DisplayPort, Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI), or analog (D-sub) interface. For instance, in certain embodiments, such a standalone display 12 may be a model of an Apple Cinema Display®, available from Apple Inc.
Although an electronic device 10 is generally depicted in the context of a computer in
In another embodiment, the electronic device 10 may also be provided in the form of a portable multi-function tablet computing device (not illustrated). In certain embodiments, the tablet computing device may provide the functionality of two or more of a media player, a web browser, a cellular phone, a gaming platform, a personal data organizer, and so forth. By way of example only, the tablet computing device may be a model of an iPad® tablet computer, available from Apple Inc.
With the foregoing discussion in mind, it may be appreciated that an electronic device 10 in either the form of a computer 30 (
One example of a touch-sensitive display device 34 of an electronic display device 10 is depicted in
The backlight unit 44 includes one or more light sources 48. Light from the light source 48 is routed through portions of the backlight unit 44 (e.g., a light guide and optical films) and generally emitted toward the bottom polarizer 43 and the display panel 42. In various embodiments, light source 48 may include a cold-cathode fluorescent lamp (CCFL), one or more light emitting diodes (LEDs), or any other suitable source(s) of light. Further, although the touch-sensitive display device 34 is generally depicted as having an edge-lit backlight unit 44, it is noted that other arrangements may be used (e.g., direct backlighting) in full accordance with the present technique. The polarization of the light emitted by the backlight unit 44 may be controlled by the bottom polarizer 43. In some embodiments, the bottom polarizer 43 may polarize the light emitted out from the backlight unit 44 in substantially one direction, and the light polarized by the bottom polarizer 43 may propagate towards the display panel 42.
As may be appreciated, the display panel 42 may include an array of pixels configured to selectively modulate the amount and color of light passing from the backlight unit 44 through the bottom polarizer 43. For example, the display panel 42 may include an LCD panel including a liquid crystal layer, one or more thin film transistor (TFT) layers configured to control orientation of liquid crystals of the liquid crystal layer via an electric field, and polarizing films, which cooperate to enable the display panel 42 to control the amount of light emitted by each pixel. Additionally, the display panel 42 may include color filters that allow specific colors of light to be emitted from the pixels (e.g., red, green, and blue). In some embodiments, color filtered light may be polarized at a top polarizer 41.
The touch-screen panel 50 may be a substantially transparent panel disposed over the display panel 42 of the touch-sensitive display device 34. The touch-screen panel 50 may include a substrate 51 having electrodes 52 which may be arranged in a matrix or grid configuration or various other suitable configurations. In some embodiments, the electrodes 52 may be placed on one side or both sides of the substrate 51. During an operation of the touch-sensitive display device 34, a user may perform various functions by touching the top surface (e.g., the glass substrate in the frame 46) of the touch-sensitive display device 34 directly over certain positions on the touch-screen panel 50 using a finger or other object. During a touch of the top surface of the touch-sensitive display device 34, a capacitance may form in the touch-screen panel 50 between the touching finger or object and the electrodes 52 corresponding to the touched position. Based on the electrode(s) 52 of the touch-screen panel 50 in which a capacitance is formed, a processor (e.g., the processor 18, or another suitable processor coupled to the touch-sensitive display device 34 and/or to the touch-screen panel 50) may calculate and determine the position of the touch with respect to the touch-screen panel 50. The touched position may correspond with user interface functions (e.g., icons 40 of the GUI 38, as illustrated in
In some embodiments, the electrodes 52 of the touch-screen panel 50 may include conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), silver, copper, aluminum, or other suitable metals. The substrate 51 of the touch-screen panel 50 over which the electrodes 52 are disposed may include a suitable transparent materials, such as glass, plastic, etc. The electrodes 52 may significantly reflect light, and may also have different light reflection and transmission properties than the substrate 51 of the touch-screen panel 50.
For example,
Light may be transmitted and reflected differently throughout the touch-screen panel 50 due to different light reflection and transmission properties of the electrodes 52 and the substrate portions 51 of the touch-screen panel 50. For example, the transmitted light T1 which travels through the substrate portion 51 and an electrode 52 of the touch-screen panel may be smaller (e.g., having a lower light intensity, having lower visual perceptibility) than the transmitted light T2 through only the substrate portion 51 of the touch-screen panel 50. Further, the reflected light R1 which is reflected from the electrode 52 may be greater (e.g., having a higher light intensity, having higher visual perceptibility) than the reflected light R2 which is reflected from the substrate portion 51 of the touch-screen panel 50.
Such light transmission and reflection properties of the touch-screen panel 50 may result in undesirable visual effects on the touch-sensitive display device 34. For instance, the reflected light R1 and R2 may be perceived as glare on the image displayed by the touch-sensitive display device 34. Moreover, due to the different light transmission and reflection properties of the substrate portion 51 and the electrodes 52, the electrodes 52 may be visibly perceptible to a user, particularly in bright ambient light conditions, such as under direct sunlight or under a lamp. Such visibility of the electrodes 52 may interfere with a user's viewing of the images displayed by the touch-sensitive display device 34.
In one or more embodiments, as illustrated in
The circular polarizer 54 may significantly decrease the amount of reflected light R1 and R2 which exits the top surface of the top substrate 56 to be perceived by a user. As illustrated in
The linearly polarized light 64 may then pass through the quarter-wave plate 60, also referred to as a quarter-wave retardation film 60. The quarter-wave plate 60 may include one or multiple layers which, as a whole, is configured to optically retard (i.e., shift) the phase of light by approximately a quarter of the wavelength of the light. Generally, the quarter-wave plate 60 may shift the phase of the linearly polarized light 64 to make a 45° angle with the axis of travel of the light 64, resulting in changing the polarization of the linearly polarized light 64 to circularly polarized light. In one embodiment, the linearly polarized light 64 may pass through the quarter-wave plate 60 to become left-circularly polarized light 66. In some embodiments, the left-circularly polarized light 66 may be substantially circularly or elliptically polarized.
The left-circularly polarized light 66 may be reflected from the touch-screen panel 50 (e.g., from an electrode 52 or a substrate portion 51). As circularly polarized light typically changes orientation by a π/2 phase shift when it is reflected from a surface, the left-circularly polarized light 66 is reflected from the electrode 52 as right-circularly polarized light 68. The right-circularly polarized light 68 may pass through the quarter-wave plate 60, which again shifts the phase of the right-circularly polarized light 68, such that linearly polarized light 70 passes through the quarter-wave plate 60 after reflection at the electrode 52. The linearly polarized light 70 has a linear polarization which is substantially parallel to the direction of travel (e.g., the reflected light R1). As the linearly polarized light 70 has a polarization that is perpendicular to the polarization of the linear polarizer 58, the linearly polarized light 70 may be substantially absorbed by the linear polarizer 58. Therefore, when external light travels through the circular polarizer 54 and is reflected from the electrode 52 or another portion of the touch-screen panel 50, the reflected light R1 is absorbed by the circular polarizer 54, such that light reflections which may be perceived as glare or visible electrodes may be substantially reduced.
While
In different embodiments, the circular polarizer 54 may have various orientations. For instance, the linear polarizer 58 is not limited to a polarization direction that is perpendicular to the direction of light traveling toward the touch-screen panel 50, as described with respect to
Furthermore, while a capacitive touch-screen panel is described as one example of the touch-screen panel 50, in accordance with the present techniques, the circular polarizer 54 may reduce undesirable light reflections and/or transmissions from or through touch-screen panels 50 of various configurations. For example, in some embodiments, the circular polarizer 54 may reduce surface reflections and/or transmissions from resistive or infrared touch-screen panels 50.
Moreover, the present techniques of implementing a circular polarizer over a touch-screen panel may be applied to any suitable display device having a touch-screen panel. While LCDs are used as an example in this disclosure, the present techniques may also be implemented on other types of display devices, such as OLEDs.
The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.