Abstract:
A method of operating a light emitting, image display device that is configured to normally display to one or more viewers, a corresponding image thereof with a relatively wide viewing angle and relatively good contrast, includes selectively outputting to one or more peripheral portions of the wide viewing angle, privacy-protecting light rays of sufficient luminance to substantially reduce, for corresponding viewers viewing from the respective one or more peripheral portions of the relatively wide viewing angle, the otherwise normal and relatively good contrast of the image so as to thereby inhibit viewing of the image from the respective one or more peripheral portions. In one embodiment, the method is carried out using an organic light emitting diode (OLED) panel and a light source part disposed on a backside of the OLED panel and comprising at least one light guide plate and at least one light source.

Description:
PRIORITY STATEMENT 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2013-0050233, filed on May 3, 2013 in the Korean Intellectual Property Office (KIPO), the contents of which application are herein incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field 
     The present disclosure of invention relates to an organic light emitting display device. More particularly, the present teachings relate to an organic light emitting display device capable of controlling when a wide viewing angle thereof is available or not. 
     2. Description of Related Technology 
     An organic light emitting display device (OLEDD) is an active type thin (e.g., flat) panel display apparatus capable of displaying an image using a plurality of organic light emitting diodes (OLED&#39;s) each of which emits light itself. Because of this, the conventional organic light emitting display device works without a backlight. The organic emitting display device may have a variety of advantages such as a rapid response rate, a relatively thin thickness, an excellent color reproduction characteristics and low power consumption. 
     In particular, one of the advantages of the typical organic light emitting display device is that it has a good, wide viewing angle such that persons situated to a side of, rather than facing head on toward the screen, can easily see what is being displayed over the wide viewing angle. However, this general purpose advantage of the organic light emitting display device that is provided with a good wide viewing angle may at times be a disadvantage if it exposes private information to persons who are not intended to see the same. For example, an authorized user might be using an OLEDD-based laptop computer while seated in an airplane or in other crowded seating situations and may not want nearby strangers to easily see what is being displayed on his or her screen. Thus, in situations such as this, it may be advantageous to have an organic light emitting display device including a selectively evocable privacy protection structure, such as a veil view structure, capable of selectively protecting private information or preserving data of users. 
     It is to be understood that this background of the technology section is intended to provide useful background for understanding the here disclosed technology and as such, the technology background section may include ideas, concepts or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to corresponding invention dates of subject matter disclosed herein. 
     SUMMARY 
     Exemplary embodiments of the present disclosure of invention provide an organic light emitting display device (OLEDD) capable of selectively controlling a viewing angle thereof including selectively reducing the viewing angle for sake of privacy protection or data preservation of users. 
     According to the present teachings, an organic light emitting display device includes an organic light emitting diodes display (OLEDD) panel and a light source part disposed to project privacy-protecting light rays from a backside of the OLEDD panel. In one embodiment, the privacy-protecting light rays sourcing part includes at least one a light guide plate and at least one light source. 
     In an exemplary embodiment, one or more light sources may be disposed between two or more spaced apart light guide plates. 
     In an exemplary embodiment, the light sources may include at least one of a semiconductive light emitting diode (LED), an organic light emitting diode (OLED), a cold cathode fluorescent lamp (CCFL) or an external-electrode fluorescent lamp (EEFL). 
     In an exemplary embodiment, the organic light emitting display device may further include a wiring part disposed between the light guide plate and the light source and including wirings that electrically connect between the OLED panel and the light source. 
     In an exemplary embodiment, the light source may be disposed between a corresponding light guide plate and a corresponding portion of the wiring part. 
     In an exemplary embodiment, the light source part may further include a first light guide plate and a spaced apart second light guide plate. 
     In an exemplary embodiment, the first and the second light guide plate may be integrally combined on, or as part of a substrate with the light source and the wiring part. 
     In an exemplary embodiment, the light source part may include respective portions disposed at a first edge of the OLED panel and a second edge of the OLED panel opposite to the first edge of OLED panel. 
     In an exemplary embodiment, energizing power may be applied to the light source through a touch panel or additional switches. 
     In an exemplary embodiment, the light source part may be electrically connected to the OLED panel, and may be selectively energized or de-energized by user operation of the OLED panel  400 . 
     In an exemplary embodiment, a thickness of the light guide plate may be increased gradually toward a direction of disposed the light source. 
     In an exemplary embodiment, the light guide plate may include a rectangular shape in a plan view. 
     In an exemplary embodiment, the OLED panel may emit light in a first direction, and the light source may emit light in a second direction different from the first direction. 
     In an exemplary embodiment, the first direction may form a viewing angle between about 0 degrees and about 60 degrees and the second direction may form a viewing angle between about 60 degrees and about 90 degrees. 
     According to the exemplary embodiments of the present disclosure, an organic or other such light emitting, image display device may include the light source part in a backside of the image displaying panel to control a recognition area by a user selection, thereby protecting private information or preserving data privacy of users. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present disclosure of invention will become more apparent by describing in detailed exemplary embodiments thereof with reference to the accompanying drawings, in which: 
         FIG. 1  is cross-sectional view illustrating an organic light emitting display device in accordance with an exemplary embodiment; 
         FIG. 2  is a cross-sectional view illustrating the organic light emitting display device (OLEDD) in  FIG. 1  when power is applied to activate the privacy-protecting light rays sourcing part; 
         FIG. 3  is a plan view illustrating a possible layout for the organic light emitting display device in  FIG. 1 ; 
         FIG. 4  is a cross-sectional view illustrating an organic light emitting display device in accordance with another exemplary embodiment; 
         FIG. 5  is a cross-sectional view illustrating an organic light emitting display device in accordance with still another exemplary embodiment; and 
         FIG. 6  is a graph illustrating a relationship between a viewing angle and luminance of the organic light emitting display device in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Various example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some example embodiments are shown. The present inventive concept may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present inventive teachings to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. Like numerals refer to like elements throughout. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present inventive concept. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present inventive concept. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept most closely pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present teachings and should not be instead interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, exemplary embodiments in accordance with the present disclosure of invention will be explained in detail with reference to the accompanying drawings. 
       FIG. 1  is cross-sectional view illustrating an organic light emitting display device (OLEDD) having a privacy-protecting light rays sourcing part in accordance with an exemplary embodiment of the present disclosure of invention. 
     Referring to  FIG. 1 , an organic light emitting display device  10  may include an organic light emitting diode (OLED) panel  400  and a selectively activatable privacy-protecting light rays sourcing part  100  disposed behind (e.g., under) the organic light emitting diode panel  400  such that the latter can function as a shield against privacy-protecting light rays projected from the sourcing part  100  (or “light source part”  100 , for short). 
     The light source part  100  includes a first light guide plate  101  disposed to project privacy-protecting light rays from a respective first side, a second light guide plate  102  disposed to project privacy-protecting light rays from a respective second side, a plurality of light sources  103  operatively coupled to the light guide plates ( 101 ,  102 ) and a wiring part  104  operatively coupled to the light sources  103 . 
     The light source part  100  is either permanently or removably affixed to a back side of the OLED panel  400 . The light source part  100  may be selectively energized by computer driven actuation through the OLED panel  400  or manually energized by a user. More specifically, a user may be provided with an additional switch or a touch panel icon for selectively activating and deactivating the light source part  100 . 
     More specifically, the first light guide plate  101  is disposed under a left side of the OLED panel  400 . The first light guide plate  101  may include an inclined upper surface inclined toward a left-side, wide angle viewing area portion of the OLED panel  400 . The first light guide plate  101  may include a flat lower surface. As a result of the inclined top surface, a thickness of the first light guide plate  101  increases gradually when considering it from its outer edge and moving toward the centrally located light sources  103 . The first light guide plate  101  may have a rectangular shape when viewed in top plan view. (See  FIG. 3 .) The first light guide plate  101  may guide light supplied from the light sources  103 . 
     Alternatively, the first light guide plate  101  may include an inclined lower surface inclined toward the end portion of the first light guide plate  101 , while the first light guide plate  101  may include a flat upper surface. 
     The second light guide plate  102  is disposed under a right side of the OLED panel  400 . The second light guide plate  102  may include an inclined upper surface inclined toward the corresponding right-side, wide angle viewing area portion of the OLED panel  400 . The second light guide plate  102  may include a flat lower surface. A thickness of the second light guide plate  102  may be increased gradually toward the light source  103 . The second light guide plate  102  may have a rectangular shape when viewed in a top plan view. The second light guide plate  102  may guide light from the light sources  103 . 
     Alternatively, the second light guide plate  102  may include an inclined lower surface inclined toward the end portion of the second light guide plate  102 , while the second light guide plate  102  may include a flat upper surface. 
     The first light guide plate  101  and the second light guide plate  102  may include optical transmission materials such as at least one of PMMA (poly methylmethaacrylate), PC (polycarbonate), acrylic, silicon, etc. 
     The light sources  103  are disposed between the first light guide plate  101  and the second light guide plate  102  to serve as a light source in the organic light emitting display device  10 . For example, the light source  103  may include white light emitting diodes, red light emitting diodes, green light emitting diodes, blue light emitting diodes, cold cathode fluorescent lamps, external electrode fluorescent lamps, etc. 
     The wiring part  104  is disposed between the first light guide plate  101  and the second light guide plate  102 . The wiring part  104  may include wirings (not individually illustrated) that electrically connect the OLED panel  400  and the light sources  103 . 
     As illustrated in  FIG. 1 , when power is not applied to the light source  100 , the light source  100  does not emit privacy-protecting light rays. In this case, the organic light emitting display device  10  may widely display a first image both in a first direction A and in a second direction B because of the wide viewing angle properties of the OLEDD  10 . The first direction A is a front direction corresponding to about 0 degree to about 60 degrees of a viewing angle from a normal plane centered in the middle of the screen. The second direction B is a side direction corresponding to about 60 degrees to about 90 degrees of a viewing angle from a normal plane centered in the middle of the screen. 
     A general or flexible organic light emitting diode panel may be used for the OLED panel  400 . 
       FIG. 2  is a cross-sectional view illustrating the organic light emitting display device in  FIG. 1  when power is applied for emitting privacy-protecting light rays out of both the left and right sides. 
     Referring to  FIG. 2 , when energizing power (e.g., a supply voltage of appropriate level) is applied to the light source part  100  of the organic light emitting display device (OLEDD)  10  by a user, light rays irradiated from the light source part  100  are guided and emitted out of left and right side portions of the device  10 , for example in the second directions B but in the first direction A due to light ray re-directing functions of the first light guide plate  101  and of the second light guide plate  102  and due to shielding in the A direction as provided by the back of the OLEDD  10 . Accordingly, when a user drives the light source part  100  of the organic light emitting display device  10 , the organic light emitting display device  10  may display only a viewable first image in the first direction A but not in the B directions. That is, when a user manually and/or by means of automatic software control, energizes part or all of the light source part  100  of the organic light emitting display device  10 , a second image in the second direction B may not be viewable by persons looking along a reverse of that direction B because the privacy-protecting light rays output in the B direction prevent or substantially interfere with usable viewing along the B portions of the wide angle capabilities of the OLEDD  10 . In  FIG. 2 , the B directed privacy-protecting light rays are drawn in schematic fashion. The left and right edges of the OLEDD  10  may be transparent or otherwise light-passing to let through the privacy-protecting light rays when the sourcing part  100  is activated, and/or the left and right edges of the light guide plates,  101  and  102 , may extend beyond the left and right edges of the OLEDD  10  such that the privacy-protecting light rays are projected toward areas where viewing is to be cloaked by means of the outward extending parts of the light guide plates,  101  and  102 . 
       FIG. 3  is a top plan view illustrating a possible layout for the organic light emitting display device in  FIG. 1 . 
     Referring to  FIG. 3 , the light source part  100  of the illustrated embodiment includes a rectangle shaped first light guide plate  101 , a rectangle shaped and spaced apart second light guide plate  102 , a plurality of the light sources  103  disposed in the spacing between the light guide plates, and a wiring part  104  also disposed in the spacing between the light guide plates. In the illustrated embodiment, the light sources  103  are arranged alternately and distributively in an elongation direction of the wiring part  104  so as, for example, to provide for better heat dissipation than if the light sources were crowded together. 
     An area of the first light guide plate  101  may be greater than an area of the wiring part  104  in a plan view. An area of the second light guide plate  102  may be greater than an area of the wiring part  104  in a plan view. Alternatively, an area of the first light guide plate  101  and the second light guide plate  102  may be smaller than an area of the wiring part  104  in a plan view. The exemplary rectangular shapes of the light guide plates,  101  and  102 , are merely that, namely, exemplary and in alternate embodiments, the light guide plates may have portions which interdigitate with one another such that each light source  103  can simultaneously output its light rays to both adjacent and interdigitated fingers (not shown) of the alternatively interdigitated light guide plates. In the illustrated example of  FIG. 3 , however, it may be assumed that the light sources  103  on the left output their respective privacy-protecting light rays only to the left side light guide plate  101  and that the light sources  103  on the right output their respective privacy-protecting light rays only to the right side light guide plate  102  whereby, in appropriate circumstances only the left or the right side light sources are activated so as to conserve power and/or allow a person only sitting on one side of the user to see what is being displayed. 
       FIG. 4  is a cross-sectional view illustrating an organic light emitting display device in accordance with another exemplary embodiment. 
     Referring to  FIG. 4 , an organic light emitting display device  20  includes a light source part  200  and an organic light emitting diodes display (OLEDD) panel  400 . 
     The organic light emitting display device  20  is substantially the same as or similar to the organic light emitting display device  10  illustrated in  FIG. 1  except for a detailed structuring of the light source part  100 . Thus, detailed descriptions of like elements will not be repeated herein. 
     The light source part  200  includes a first light guide plate  201 , a second light guide plate  202 , a light source  203  and a wiring part  204 . 
     The light source part  200  is electrically connected to the OLEDD panel  400 . The light source part  200  is selectively driven by a user (or by automated software) through the OLEDD panel  400 . A user may provide activating input through additional switches or a touch panel or various software actuations to drive the light source part  200  and thus activate part or all of the privacy-protecting light rays sourcing functions of the light source part  200 . 
     The first light guide plate  201  is disposed under a left side of the OLED panel  400 . The first light guide plate  201  may include an inclined upper surface inclined toward an end portion of the first light guide plate  201 . The first light guide plate  201  may include a flat lower surface. A thickness of the first light guide plate  201  may be increased gradually toward the light source  203 . The first light guide plate  201  may have a rectangular shape when viewed in a top plan view. The first light guide plate  201  may serve to guide light from the light source  203 . 
     Alternatively, the first light guide plate  201  may include an inclined lower surface inclined toward of the end portion of the first light guide plate  201 , while the first light guide plate  201  may include a flat upper surface. 
     The second light guide plate  202  is disposed under a right side of the OLED panel  400 . The second light guide plate  202  may include an inclined upper surface inclined toward an end portion of the second light guide plate  202 . The second light guide plate  202  may include a flat lower surface. A thickness of the second light guide plate  202  may be increased gradually toward the light source  203 . The second light guide plate  202  may have a rectangular shape when viewed in plan view. The second light guide plate  202  may serve to guide light from the light source  203 . 
     Alternatively, the second light guide plate  202  may include an inclined lower surface inclined toward the end portion of the second light guide plate  202 , while the second light guide plate  202  may include a flat upper surface. 
     The first light guide plate  201  and the second light guide plate  202  may be composed of appropriate optics transmission materials such as for example including at least one of PMMA (poly methylmethaacrylate), PC (polycarbonate), acrylic, silicon, etc. 
     The light source  203  is disposed between the first light guide plate  201  and the second light guide plate  202 , and serves as a light source in the organic light emitting display device  20 . 
     The wiring part  204  may electrically connect the OLED panel  400  and the light source  203 . An area of the wiring part  204  may be larger than an area of the first light guide plate  201  in a plan view. An area of the wiring part  204  may be larger than an area of the second light guide plate  202  in a plan view. The light source part  203  and the wiring part  204  may be integrally connected with each other. More specifically, the electrical conductors (not shown) of the wiring part  204  may be monolithically integrated onto a same substrate on which the light sources  203  (e.g., LED&#39;s, OLED&#39;s) are mounted and the substrate may integrally provide the light guide plate functions or have appropriate light guide plates also mounted to it. 
       FIG. 5  is a cross-sectional view illustrating an organic light emitting display device in accordance with still another exemplary embodiment of the present disclosure of invention. 
     Referring to  FIG. 5 , an organic light emitting display device  30  includes a plurality of light source parts  300   a ,  300   b  and an organic light emitting diode (OLED) panel  400 . 
     The organic light emitting display device  30  is substantially the same as or similar to the organic light emitting display device  10  illustrated in  FIG. 1  except for a specific structuring of the light source parts  300  into a plurality of spaced apart light source parts  300   a ,  300   b . Thus, detailed descriptions of like elements will not be repeated herein. 
     In this embodiment, a plurality of the light sources parts may be disposed under both sides of the OLED panel  400 . A first light source part  300   a  may be disposed under a left side of the OLED panel  400 . A spaced apart and second light source part  300   b  may be disposed under a right side of the OLED panel  400 . 
     Each of the light source parts  300   a ,  300   b  includes a respective light guide plate  301 , a respective plurality of light sources  303  and a respective wiring part  304 . 
     The light source part  300  is electrically connected to the OLED panel  400 . The light source part  300  is selectively driven by a user through the OLED panel  400 . A user may input through additional switches or a touch panel to drive the light source part  100 . 
     A light guide plate  301  is disposed under the OLED panel  400 . The light guide plate  301  may have an inclined upper surface inclined toward an end portion of the first light guide plate  301 . The first light guide plate  101  may include a flat lower surface. The light guide plate  301  may include as its optical transmission materials, at least one of PMMA (poly methylmethaacrylate), PC (polycarbonate), acrylic, silicon, etc. A thickness of the light guide plate  301  may be increased gradually toward the light sources  303 . The light guide plate  301  may have a rectangular shape in plan view. The light guide plate  301  may serve to guide light from the light source  303 . 
     Alternatively, the light guide plate  301  may have an inclined lower surface inclined toward the end portion of the light guide plate  301 , while the light guide plate  301  may have a flat upper surface. 
     A plurality of the light sources  303  is connected to the light guide plate  301 , and serves as a light source in the organic light emitting display device  30 . 
     The wiring part  304  provides a pathway for wirings that connect the light source  303  and the OLED panel  400 . An area of the wiring part  304  may be larger than an area of the light guide plate  301  in a plan view. Alternatively, an area of the light guide plate  301  may be larger than an area of the wiring part  304 . In this embodiment, the light source  303  is disposed between the light guide plate  301  and the wiring part  304 . The wiring part  304  may electrically connect the OLED panel  400  and the light source  303 . 
       FIG. 6  is a graph illustrating a relationship between a viewing angle and luminance of the organic light emitting display device in  FIG. 1 . 
     Referring to  FIG. 6 , when energizing power (e.g., a voltage) is applied to a respective portion of or all of the light source part  100 , a perceived luminance of the organic light emitting display device varies depending on a viewing angle. Here the X axis represents a viewing angle and the Y axis represents luminance curves due to the output light rays of the organic light emitting diodes panel  400  and the light source part  100 . The luminance of the organic light emitting diodes panel  400  in the first direction A, which is a viewing direction within about 0 degree and about 60 degrees, is about 300 (as measured in appropriate luminance representing units). When the organic light emitting display device is viewed on the front side in the first direction A, the luminance of the organic light emitting diode panel  400  is greater than the luminance of the light source part  100 , so that the contrast ratio of the projected image is not decreased (not interfered with by the simultaneous outputting of the privacy-protecting light rays from the sourcing part  100 ). Therefore, a user may recognize an image displayed on the organic light emitting diode panel  400  in the first direction A. However, when the organic light emitting display device is viewed in the second direction B, which is a viewing direction within about 60 degree and about 90 degree, the luminance of the organic light emitting diode panel  400  is smaller than the luminance of the light source part  100 , and if the viewer&#39;s eyes shrink their pupil size to accommodate for increased luminance, the contrast ratios within the image portion of the light rays that a person (viewer) facing in the B area sees, may be substantially decreased. Therefore, it is difficult for a user in the B facing area to recognize an image displayed on the organic light emitting diode panel  400  in the second direction B because the image is washed out by the greater luminance of the privacy-protecting light rays output from the sourcing part. 
     According to exemplary embodiments of the present disclosure of invention, an organic light emitting display devices may include the light source part in a backside of the organic light emitting diode panel to control a recognition area by a user selection, thereby protecting private information. 
     The foregoing is illustrative of the present disclosure of invention and is not to be construed as limiting thereof. Although a few exemplary embodiments in accordance with the present disclosure have been described, those skilled in the art will readily appreciate in light of the foregoing that many modifications are possible without materially departing from the novel teachings and advantages of the present disclosure of invention. Accordingly, all such modifications are intended to be included within the scope of the present teachings. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also functionally equivalent structures.