Abstract:
A touch display panel assembly is provided. The touch display panel assembly includes a display panel having a display surface on a side of the display panel for emitting light, a touch light detector at a periphery of the display panel for detecting the emitted light and having an iris that faces in a direction substantially normal to the display surface for passing the emitted light into the touch light detector, and a light guide above the iris for guiding the emitted light from the display surface to the iris and into the touch light detector. The touch display panel assembly has an improved viewing angle and can be made thinner as compared to conventional touch display panels due to the improved features of the touch light detector.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/084,584, filed on Jul. 29, 2008, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a touch display panel, and more particularly, to a touch display panel having an improved light detector that recognizes a touch function by detecting a change of light. 
         [0004]    2. Description of the Related Art 
         [0005]    A touch panel can be an infrared ray, resistance film, electrostatic capacitive, ultrasonic wave, or pressure sensor type touch panel. An optical type touch panel, such as an infrared ray type touch panel, can be used for large screens, such as a plasma display panel. 
         [0006]    An existing touch display panel has touch light detectors that include two reflection mirrors, which respectively extend along the edges of a flat display panel orthogonal to each other. The reflection mirrors have reflection planes facing toward a display unit side of the flat display panel, and are attached at a 45 degree angle with respect to an inner side of the display panel. The touch light detector further includes two light receivers, which face the two reflection mirrors on the opposite edges that face the edges where the two reflection mirrors are attached. Accordingly, the two light receivers and the reflection mirrors protrude from the surface of the flat display panel, thereby increasing the entire thickness of the flat display panel assembly. 
       SUMMARY OF THE INVENTION 
       [0007]    An aspect of an embodiment of the present invention is directed toward a touch display panel having improved features in detecting a user&#39;s touch function by detecting changes of light. 
         [0008]    In one embodiment, the touch display panel includes a display panel having a display surface on a side of the display panel for emitting light, a touch light detector at a periphery of the display panel for detecting the emitted light and having an iris for allowing the emitted light to pass into the touch light detector, and a light guide above the iris for guiding the emitted light from the display surface to the iris and into the touch light detector. The iris faces in a direction substantially normal to the display surface. 
         [0009]    In one embodiment, the light guide includes a reflection mirror having a reflection surface with an incline to reflect the light from the display surface toward the iris. The reflection surface may be a curved surface, or more particularly, can be a convex mirror. The light guide may further include a visible light blocking filter and a support coupled to the reflection mirror and the touch light detector to maintain an inclination angle (θ 1 ) between the reflection surface and the display surface. 
         [0010]    In certain embodiments, the reflection mirror has a slit with one horizontal stripe or multiple stripes, where a first stripe extends in a first direction, and a second stripe extends in a second direction crossing the first direction. 
         [0011]    The touch display panel may further include a bracket for coupling the touch light detector to a chassis base at the periphery of the display panel, and the touch light detector is between the bracket and the reflection mirror. 
         [0012]    In one embodiment, the light guide is a prism having a density value to direct the light from the display surface to the iris. The density value of the prism is a value in which the prism provides a substantially total reflection of the light. The prism may be placed in position such that it completely or substantially covers the iris. In one embodiment, the prism has a concave surface facing toward the display surface. The prism may be attached to the periphery of the iris by an adhesive. In one embodiment, the adhesive has a density value substantially identical to that of the prism and is between the prism and the iris and covering the iris. 
         [0013]    In one embodiment, the touch display panel includes at least two touch light detectors, each located at a corner of the display panel. The touch light detector may include a housing, the iris being in the housing, and a lens located inside the housing. The iris may be smaller in size than the lens and the lens may have a viewing angle of about 65°. In one embodiment, the light guide is configured to increase the viewing angle of the lens to about 90°. 
         [0014]    According to another embodiment, the display panel includes a first substrate, a second substrate spaced from and facing the first substrate, a phosphor between the first substrate and the second substrate, and a plurality of discharge electrodes for generating vacuum ultraviolet rays to excite a phosphor material of the phosphor layer. When the display panel emits an infrared ray(s), the touch light detector is configured to detect a variation of the emitted infrared ray(s). In one embodiment, the touch light detector further includes an infrared transmission filter in a light path between the display surface and a lens of the touch light detector. 
         [0015]    Another aspect of an embodiment of the present invention is directed toward a plasma display device, which includes the display panel, and the touch light detector. In one embodiment, the plasma display device further includes a front cabinet and a back cover for containing the display panel. The front cabinet may have a portion covering the touch light detector and the light guide. 
         [0016]    In certain embodiments, the touch display panels of the present invention are thin or have a small or minimal thickness by reducing or minimizing the thickness of the touch light detector. The touch display panel according to various embodiments of the present invention also has an improved touch light detector with a wider view angle (or wider viewing angle). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
           [0018]      FIG. 1  is an exploded perspective view of a plasma display device, according to an embodiment of the present invention; 
           [0019]      FIG. 2  is an enlarged perspective view of the touch light detector of  FIG. 1 ; 
           [0020]      FIG. 3  is a cross-sectional view of the touch light detector of  FIG. 1 ; 
           [0021]      FIG. 4  is a plan view illustrating a mechanism of detecting lights of a touch light detector according to an embodiment of the present invention; 
           [0022]      FIG. 5A  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area X using a negative method; 
           [0023]      FIG. 5B  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area Z using a negative method; 
           [0024]      FIG. 5C  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area Y using a negative method; 
           [0025]      FIG. 5D  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area X using a positive method; 
           [0026]      FIG. 5E  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area Z using a positive method; 
           [0027]      FIG. 5F  is an infrared ray graph illustrating a detection of an infrared ray(s) in an area Y using a positive method; 
           [0028]      FIG. 6  is a plan view of a reflection mirror according to an embodiment of the present invention; 
           [0029]      FIG. 7  is a plan view of another reflection mirror according to another embodiment of the present invention; 
           [0030]      FIG. 8  is a plan view of another reflection mirror according to yet another embodiment of the present invention; 
           [0031]      FIG. 9  is an enlarged perspective view of a touch light detector according to an embodiment of the present invention; and 
           [0032]      FIG. 10  is a cross-sectional view of the touch light detector of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    In the following detailed description, only certain exemplary embodiments of the present invention are shown and described, by way of illustration. As those skilled in the art would recognize, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Also, in the context of the present application, when an element is referred to as being “on” another element, it can be directly on another element or be indirectly on another element with one or more intervening elements interposed therebetween. Like reference numerals designate like elements throughout the specification. 
         [0034]    Referring to  FIG. 1 , a plasma display device  100  includes a touch display panel, a filter assembly  120  attached in front of the touch display panel, a chassis base (or chassis base assembly)  130  installed at the back of the touch display panel, and a case  140  containing the touch display panel, the filter assembly  120 , and the chassis base  130 . In one embodiment, the touch display panel includes a display panel (or panel assembly)  110 , a touch light detector  200 , and a light guide to direct light into the touch light detector  200 , all of which shall be described in further detail below. 
         [0035]    The display panel  110  includes a first substrate  111  and a second substrate  112  facing the first substrate  111 . A sealing member, such as frit glass, is coated on inner facing edges of the first and second substrates  111  and  112 , thereby sealing a discharge space between the first and second substrates  111  and  112 . 
         [0036]    Referring also to  FIG. 3 , the plasma display device  100  exhibits different numerical and graphical displays by gas and phosphor excitation. In one embodiment, the gas and phosphor excitation process is achieved by injecting and sealing the discharge gas in the display panel  110 , where a plurality of discharge electrodes  113  and  114  are disposed, applying a discharge voltage to the plurality of discharge electrodes  113  and  114  (in  FIG. 3 ), and exciting a phosphor material of a phosphor layer  115  by using a vacuum ultraviolet ray generated by the applied discharge voltage. The plasma display device  100  emits infrared ray(s) (dotted line) along with ultraviolet ray(s) during gas discharge. 
         [0037]    Referring back to  FIG. 1 , the filter assembly  120  is directly attached to the front surface of the first substrate  111 , which is a substrate that allows visible light to pass through. The filter assembly  120  includes a plurality of films stacked on one another in order to reduce or prevent reflection of external lights, neon radiations, and/or electromagnetic waves generated from the display panel  110 . 
         [0038]    In addition, the chassis base  130  includes a base attached to the back of the display panel  110  by an adhesive member, a circuit board attached to the back of the base, and a circuit device mounted on the circuit board. A terminal of a signal transmitter  131 , such as a flexible printed cable is electrically connected to the circuit board, and another terminal of the signal transmitter  131  is electrically connected to terminals of each of the discharge electrodes  113  and  114  of the display panel  110 . A cover plate  132  can further be included and installed below the chassis base  130  to protect any part where the signal transmitter  131  is installed. 
         [0039]    The case  140  includes a front cabinet  141 , which is installed in front of the filter assembly  120 , and a back cover  142 , which is installed at the back of the chassis base  130 . A plurality of air through-holes  143  are formed in the top and bottom of the back cover  142 . 
         [0040]    In one embodiment, the plasma display device  100  includes a touch light detector  200  (e.g., an infrared light sensor) composed of a plurality of touch light detectors  210  and  220 . The touch light detector  210 ,  220 , which detects changes in infrared rays, is installed at an edge of the display panel  110 . 
         [0041]    The infrared rays may be generated from an infrared ray generating apparatus or the plasma display device  100 , but is not limited thereto. In one embodiment, the infrared ray is generated from the plasma display device  100  itself. 
         [0042]    Referring to  FIGS. 2 and 3 , the touch light detector  200  (or a part of the touch light detector  200 ) is installed at a corner of the display panel  110 . The touch light detector  200  includes a sensor housing unit  201  and a lens  202  installed inside the sensor housing unit  201 . The touch light detector  200  photographs objects via an iris  203  formed in front of the sensor housing unit  201 . The iris  203 , which allows light to pass, is generally smaller than a lens and a charged-coupled device (CCD). In one embodiment, light rays are allowed to pass through the iris  203  by a small mirror adjacently located to the iris  203 . The mirror  204  changes the direction of the light rays, thereby passing them through the iris  203 . 
         [0043]    Referring to  FIG. 4 , there is shown the first touch light detector  210 , which is installed at an upper corner of the display panel  110 , and the second touch light detector  220 , which is installed at another upper corner. Alternatively, the touch light detectors  210  and  220  can be installed at the lower corners of the display panel  110 . The touch light detector  210 ,  220  may be provided in any form so long as it is installed at a corner of the display panel. 
         [0044]    The touch light detectors  210  and  220  may include one or more features of the touch light detector  200 . In one embodiment, the touch light detectors  210  and/or  220  are the same as the touch light detector  200 . 
         [0045]    Referring back to  FIG. 3 , in an embodiment, the iris  203  is formed to face in a direction normal or substantially normal to a screen of the display panel  110 . Accordingly, the touch light detector  200  cannot by itself detect any infrared rays emitted from the display panel  110 . 
         [0046]    To remedy this, a light guide, such as a reflection mirror  204 , is installed above the iris  203  to direct and/or reflect infrared rays emitted from the surface of the display panel  110 . 
         [0047]    Here, since the touch light detector  200  is installed at the corner of the display panel  110 , instead of above the display panel  110 , a height H 1  of the touch light detector  200  may be substantially the same as the thickness T 1  of the display panel  110 . Moreover, since the size of the iris  203  is small, a small size reflection mirror  204  can be used. In this way, the overall thickness of the plasma display device  100 , which includes the display panel  110  and the touch light detector(s), can be reduced or minimized. 
         [0048]    A view angle (or viewing angle) of the touch light detector  200  is generally 90°, but since the view angle of a conventional lens is generally 65°, the reflection mirror  204  as previously described, may be modified, or an additional lens can be used to gain an additional view angle of 25°. 
         [0049]    The reflection mirror  204  may have a curved surface, like a convex mirror. A camera lens may include a filter (e.g., and infrared transmitter filter) that allows only infrared rays to pass through and blocks other lights, thereby protecting the touch light detector  200  from any camera malfunction that is caused by visible light or the like. 
         [0050]    Referring back to  FIG. 2 , a reflection supporter  205  is installed at the back of the reflection mirror  204  and fixed in front of the sensor housing unit  201 . The reflection supporter  205  may have the same inclination angle as the reflection mirror  204 , so that the reflection mirror  204  can maintain a set or predetermined angle θ 1  with the iris  203 . 
         [0051]    A bracket  206  is installed below the sensor housing unit  201 , so that the light detector  200  can be mounted in front of the chassis base  130 . 
         [0052]    Operations of the light detector  200  will now be described with reference to  FIGS. 4 and 5A  through  5 F. 
         [0053]    When the plasma display device  100  of  FIG. 1  is activated, infrared rays are emitted from the surface of the display panel  110 . When a user touches areas X, Y, and Z of the surface of the display panel  110 , and blocks certain pathway of lights, an infrared ray graph can be generated based on the changes in the amount of light detected by the first and second touch light detectors  210  and  220 . 
         [0054]    In other words, when each of the areas X, Y, and Z is touched, each of the first touch light detector  210  installed at the left upper corner of the display panel  110  and the second touch light detector  220  installed at the right upper corner of the display panel  110  detects the infrared rays in the touched areas X, Y, and Z via the iris  203  through the reflection mirror  204 . 
         [0055]    The detected infrared rays are then used to generate graphs A and B, where the first infrared ray graph A is generated from the infrared rays detected by the first touch light detector  210 , and the second infrared ray graph B is generated from the infrared rays detected by the second touch light detector  220 . Information generated from the first and second touch light detectors  210  and  220  is used to calculate the locations of the touched areas X, Y, and Z using an algorithm based on the angles of the touched areas X, Y, and Z, and the distance between the first and second touch light detectors  210  and  220 . 
         [0056]    For example, as illustrated in  FIGS. 5A through 5C , a negative method may be used, where the location is calculated by detecting whether the amount of light decreased in the touched area X, Y, or Z. Alternatively, as illustrated in  FIGS. 5D through 5F , a positive method may be used, where the location is calculated by detecting whether the amount of light increased in the touched area X, Y, or Z. In the present invention, any of these two methods can be used; however, the method of calculating the location is not limited thereto. 
         [0057]    In various embodiments, the display panel  110  includes the first and second touch light detectors  210  and  220  to achieve a viewing angle of 90° (arrows in a dotted line and a solid line) because each of the first and second touch light detectors  210  and  220  has the reflection mirror  204  installed above the iris  203 . As such, the touch light detectors  210  and  220  can cover the entire area of the display panel  110 . 
         [0058]      FIGS. 6 through 8  are plan views of modified examples of the reflection mirror  204 . 
         [0059]    Referring to  FIG. 6 , a reflection mirror  600  includes a slit  601 . In one embodiment, the slit  601  is formed to reduce or prevent unnecessary light from entering and can also be used to facilitate the installation of the reflection mirror  600 . The slit  601  may be a strip formed in a horizontal direction at the center of the reflection mirror  600 . The remaining area  602  may be covered with tapes or other materials using a coating process. In one embodiment, the slit  601  is formed on the front surface of the reflection mirror  600  that faces the display panel  110 . 
         [0060]    Referring to  FIG. 7 , a reflection mirror  700  includes a slit  701 , which includes a first stripe  703  crossing the center of the reflection mirror  700  in a horizontal direction, and a second stripe  704  crossing the center of the reflection mirror  700  in a vertical direction. The first and second stripes  703  and  704  intersect each other. The remaining area  702  may be covered with tapes or other materials using a coating process. In one embodiment, the slit  701  is formed on the front surface of the reflection mirror  700  that faces the display panel  110 . 
         [0061]    Referring to  FIG. 8 , a slit member  810  is arranged in front of a reflection mirror  800 . Unlike the reflection mirrors  600  and  700 , the slit member  810  is separately arranged in front of the reflection mirror  800 . The slit member  810  includes a slit  811  in an area corresponding to the center of the reflection mirror  800 . The slit member  810  may be attached to the front surface of the reflection mirror  800  that faces the display panel  110 , or may be spaced a distance away from the front surface of the reflection mirror  800 . 
         [0062]      FIG. 9  is an enlarged perspective view of a touch light detector  900  according to another embodiment of the present invention, and  FIG. 10  is a cross-sectional view of the touch light detector  900  of  FIG. 9 . 
         [0063]    Referring to  FIGS. 9 and 10 , a sensor housing unit  901  is provided for the touch light detector  900 , and a lens  902  is installed inside the sensor housing unit  901 . The touch light detector  900  can photograph objects through an iris  903  formed in front of the sensor housing unit  901 . The touch light detector  900  can also photograph and/or detect light rays from the display panel  110  by changing their directions using a light guide, such as a small prism  904  located adjacent to the iris  903 , so that the light rays can pass through the iris  903 . 
         [0064]    The iris  903  is formed facing in a direction normal or substantially normal to a screen of the display panel  110  at a corner of the display panel  110 . As such, the touch light detector  900  cannot by itself detect any infrared rays emitted from the display panel  110 . Therefore, in one embodiment, the prism  904  is installed above the iris  903  to detect infrared rays emitted from the surface of the display panel  110 . Since the prism  904  has a concave curved surface, the view angle (or viewing angle) of the iris  903  increases. The prism  904  may be attached to the top of the iris  903  by an adhesive  905  ( FIG. 10 ). In one embodiment, the prism  904  may be attached to the periphery of the iris by an adhesive. In another embodiment, the adhesive has a density value substantially identical to that of the prism and is between the prism and the iris and covering the iris. 
         [0065]    Since the touch light detector  900  is installed at the corner of the display panel  110 , instead of the top surface of the display panel  110 , a height H 2  of the touch light detector  900  can be substantially equal to the thickness T 2  of the display panel  110 . Also, since the size of the iris  903  is small, the prism  904  having a small size can be used, and thus the entire thickness of the display panel  110  and the touch light detector can be reduced or minimized. 
         [0066]    The prism  904  may be formed of a material having a density value that provides a total reflection of light at a threshold angle (θ 2 ) of 45°. Nonlimiting examples of suitable materials include glass or high density plastic. Alternatively, the prism  904  may be formed of a material (or formed with a visible light block filter) that only allows infrared rays to pass through and block other lights. Accordingly, camera malfunctions that are caused by visible lights can be reduced or prevented. 
         [0067]    An equation of a density and a threshold angle of a material, such as high density plastic and glass, is as follows: 
         [0000]      θ c =arcsin( n 2 /n 1) 
         [0068]    Here, n1 denotes the density of air, n2 denotes the density of glass or a material such as high density plastic, and θc denotes a threshold angle. 
         [0069]    For example, when the density of the prism  904  formed of high density plastic is 1.41, total reflection is possible when the threshold angle is 45°. 
         [0070]    Referring back to  FIG. 9 , a bracket  906  is installed below the sensor housing unit  901 , and thus the touch light detector  900  can be installed on the front surface of the chassis base  130  of  FIG. 1 . 
         [0071]    As described above, a touch screen panel of an embodiment of the present invention can provide the following. First, manufacturing cost can be reduced because the touch function can be performed by using and sensing light of a display panel. 
         [0072]    Second, the thickness of the display panel can be reduced because the sensing unit or touch light detector is installed at the corner of the display panel. 
         [0073]    Third, a view angle (or viewing angle) is increased by installing a modified reflection mirror or a prism. 
         [0074]    While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.