Abstract:
At least a portion of a polarizing layer in the display screen is omitted or removed to temporarily disable image generation but an equivalent polarizing layer is used as a replacement or as a substitute for enabling the display of images on the screen. For instance, the omitted or removed polarizing layer can be replaced in situ or a remote polarizing layer can be substituted through which the images on the display can be seen. The selective reassembly of the display can be used for purposes of security or promotion.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to the technical field of polarization management, particularly with respect to liquid crystal displays (LCD&#39;s) for selectively forming images as well as with respect to the use of polarization for influencing appearance. 
       BACKGROUND OF THE INVENTION 
       [0002]    Liquid crystal displays (LCD&#39;s) are well known and typically used as visual display screens for numerous devices such as laptop (notebook) computers, personal digital assistants (PDAs), camera screens, cell phones, camcorders, DVD players, electronic game devices, or navigation screens, and can generally successfully operate in high-brightness environments, such as in a car, plane, boat, or a room with windows. LCD&#39;s can be arranged as transmissive backlit devices, reflective front-lit devices, or transitional hybrid devices. All three types have at least one polarizing layer that selectively allows light (either monochrome or selective colors) to pass there through to form images on the LCD screen. 
         [0003]    Typically, two electrode layers supported on glass substrates straddle a liquid crystal layer. The liquid crystals of the liquid crystal layer are arranged together with electrodes from both electrode layers in a matrix of individually controllable cells. Both substrates also support polarizing filter films. Local electric fields generated by electrode pairs associated with each cell twist the intervening liquid crystals to rotate polarization of light passing through the crystals. One of the polarizing filter films admits polarized light into the crystals and the other polarizing filter film either passes or blocks the further passage of the light depending on the polarization state of light transmitted through the liquid crystals. For producing color images, a color filter array is mounted on one of the substrates, and individual cells within defined groups are aligned with different color filters (e.g., red, green, blue). Each such group forms a pixel, and the polarization states of the cells within each group can be controlled for forming pixels having individually addressable colors. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention among its embodiments incorporates a LCD display screen that can be viewed selectively by omitting or removing at least a portion of a polarizing layer in the display screen to temporarily disable image generation and by either actively replacing the omitted or removed polarizing layer or actively substituting therefor an equivalent polarizing layer for enabling image generation within the display screen. Image generation in a similarly disabled LCD device can be enabled, for example, by replacing the polarizing layer in situ, by viewing the display screen through a remotely supported polarizing layer (e.g., a hand-held reader or polarizing glasses), or by illuminating the display screen with polarized light (e.g., a polarizing filter built into a remote light source, such as a flashlight, and projected toward the display screen). 
         [0005]    One embodiment of the invention relates to a liquid crystal display (LCD) computer monitor screen having a designated area that is intended to be viewable only by authorized viewers. Within the designated area, the LCD screen is modified by removing (or initially omitting) one or both of an inner polarizer and an outer polarizer (e.g., inner and outer polarizing films) that straddle an addressable liquid crystal layer of the screen. Once the one or more polarizers are removed, changes in the orientation of the liquid crystals within the addressable liquid crystal layer produce no appreciable changes in the display appearance. However, authorized viewers can be provided with one or more related polarizers to restore functionality to the LCD screen. For example, paired polarizers can be coupled together at one end to preserve a polarization orientation matching the relative orientations of the removed (or omitted) polarizers. Generally, this involves an orthogonal cross-polarization orientation. With an entrance space formed through a periphery of the LCD screen, the paired polarizers can be inserted as a key straddling the addressable liquid crystal layer so that images generated by the addressable liquid crystal layer can be seen in the designated area of the screen. Just one or the other of the inner or outer polarizers could be removed (or omitted), and a related single polarizer could be arranged as a key insertable through a similar entrance space to restore functionality to the LCD screen. 
         [0006]    Another embodiment of the invention features the incorporation of a polarizer into a branded item such as a product package or promotional material, preferably located in or near a retail space at which the product packages are on display for sale or promotion. In addition, an LCD monitor screen is modified by removing (or omitting) all or a portion of a polarizer required for producing images on the screen. However, the polarizer incorporated into the product package or promotional material can be related to the removed (or omitted) polarizer (e.g., having matching linear polarization, picked up together with the product package or promotional material, and oriented by a customer for viewing video images generated by the LCD monitor screen. The customer is rewarded with a unique experience and access to information denied to other customers without similarly equipped product packages or promotional material in hand. The product marketer is rewarded with direct access to individual customers with their products or promotional materials (e.g., advertizing materials) already in hand. 
         [0007]    Once so engaged with customers, other interactive communications are also made possible. For example, to initiate an advertizing message in the LCD monitor screen, the branded item incorporating the polarizer can also incorporate an RFID (Radio Frequency Identification) tag. An RFID reader can be linked to the LCD screen to initiate the advertizing message when the branded item is moved into a designated area near the LCD screen. Different RFID tags can be associated with different products so that the advertizing message that is initiated can be matched to the product or product related material (i.e., the branded item) that is moved into the designated area. Different LCD screens or different areas of the LCD screens can have differently oriented polarizers matched to differently oriented polarizers incorporated into the branded item so that more than one advertizing message can be simultaneously viewed, each triggered by a different RFID tag. The same advertizing message can be repeated in a continuous loop until the advertizing message has been displayed in its entirety one or more times for each related RFID tag equipped branded item entering the designated area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0008]      FIG. 1  is an exploded side view schematically illustrating layers of a typical LCD display device known in prior art. 
           [0009]      FIGS. 2   a  and  2   b  are front views of a typical device with and without paired polarizing layers straddling a LCD layer of a display. 
           [0010]      FIG. 3  is a similar exploded side view of a LCD display device of the present invention having one of the polarizing layers removed; 
           [0011]      FIG. 4  is a front view of a LCD display device with a polarizing layer removed and placed on a flashlight for illuminating the display. 
           [0012]      FIG. 5  is a perspective view of a device with a polarizing layer removed and replaced by a separate polarizing layer that can be temporarily aligned with the display to reveal an image. 
           [0013]      FIG. 6  is a front view of a secure identification card with polarization sensitive security features. 
           [0014]      FIG. 7  is side view of the secure identification card of  FIG. 7  showing a polarized light source and layers of the card that are exaggerated in thickness for viewing on the page. 
           [0015]      FIG. 8  is a perspective view of an LCD display screen having a secure area and a peripheral slot for inserting a pair of polarizing films into the secure area. 
           [0016]      FIG. 9  is a perspective view of a polarizer key having a pair of polarizing films shaped for inserting the polarizing films through the slot of the display screen of  FIG. 8  for activating the secure area of the display. 
           [0017]      FIG. 10  is a perspective view of a product packaging box modified to include a polarizer. 
           [0018]      FIG. 11  is a similar perspective view showing the modified product packaging box together with a LCD display monitor modified by the removal of a comparable polarizer on the display screen. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring now to embodiments of the invention in more detail,  FIG. 1  shows an exploded view of a typical LCD display device  10 . Layer  20  in the back of the display device  10  can be either a reflective surface in the case of a reflective (front-lit) LCD display device or a light source in the case of a transmissive (backlit) display device. For a transitional hybrid LCD display device, the reflective surface layer  20  can be both partially reflective and partially transmissive and be backed by a light source. 
         [0020]    Inner polarizer layer  22  (e.g., a polarizing film) selectively transmits polarized rays in particular polarization state, e.g., linearly polarized light in a given orientation. Liquid crystal layer  24  is divided into an array of individually addressable pixels, each of which can include a plurality of addressable cells for color shading. Electrode layers  23  and  25  straddle the liquid crystal layer  24  for selectively rotating the polarization of light passing through individual pixels within the liquid crystal layer  24 . Color filter layer  26  preferably includes an array of filters organized by pixel for supporting color images. An outer polarizer layer  28  selectively transmits polarized rays in a given angular orientation, preferably orthogonal to the polarization orientation of the layer  22 . Although not shown, the electrode layer  23  and the inner polarizing layer  24  are preferably supported by a first substrate, and the electrode layer  25  and the outer polarizing layer  28 , as well as the color filter layer  26 , are preferably supported by a second substrate, which substrates can be made of glass or other transmissive substances. In the preferred arrangement, only those pixels associated with rotated liquid crystal cells transmit light through both polarizing layers  22  and  28 . Alternatively, light can be transmitted through both polarizing layers  22  and  28  except for those pixels associated with rotated liquid crystal cells. 
         [0021]      FIG. 2   a  illustrates a device  30 , such as a calculator, having a typical LCD display  32  within which a viewable image  34  is displayed.  FIG. 2   b  illustrates the same device  30  in which one of the polarizing layers is removed (or omitted) from the LCD display  32 . In the modified device  30  of  FIG. 2   b  the images  34  that might otherwise be formed by patterns of relatively rotated liquid crystals lack contrast and remain practically invisible. For example, if an outer polarizer is removed, both the light that is linearly polarized by the inner polarizer and the light that is polarization rotated by the liquid crystal layer are visible with little appreciable contrast between the two polarizations. 
         [0022]      FIG. 3  illustrates an exploded view an embodiment of the invention operating under similar principles. An LCD display  40 , such as might be incorporated into the display device  30 , is manufactured without one of the polarized layers or one of the layers is removed from the manufactured LCD display  40 . The modified LCD display  40  can include a first inner polarizing layer  42  that selectively transmits polarized rays in one orientation such as from a backlit source or a reflector. A liquid crystal layer  44  is divided into an array of individually addressable pixels (or the cells within each pixel). Electrode layers  43  and  45  selectively rotate the polarization of light passing through the individual pixels (or the cells of each pixel) within the liquid crystal layer  44 . Color filter layer  46  can comprise an array of color filters for color LCDs. Missing from this combination of layers is a second polarizing layer adjacent the electrode layer  45  necessary for converting the relatively rotated liquid crystal patterns into images. For transmissive or transitional LCD displays, the polarizing layer  42  could be preceded by a light source. For reflective LCD displays the polarizing layer  42  could be preceded by a reflector, and for transitional LCD displays the reflector would be both partially reflective and partially transmissive. Transmissive substrates straddling the liquid crystal layer could also be used for supporting the polarizing layer  42 , the two electrode layers  43  and  45 , and the color filter layer  46 . 
         [0023]      FIG. 4  illustrates a visual aid  50  intended for use with the modified LCD display  40 . The visual aid  50  contains a polarizing layer  52  that selectively transmits polarized rays in a particular orientation as a substitute for the missing polarizing layer of the LCD display  40 . The visual aid  50  together with the polarizing layer  52  can be oriented through a range of angles with respect to the polarization orientation of the polarizing layer  42  including an orientation within an orthogonal plane that completes the image of the LCD display  40 . 
         [0024]    The visual aid  50  can take the form of a flashlight in which the polarizing layer  52  located between a light source  54  and the liquid crystal layer  44  of the modified LCD display  40 . Preferably, the polarizing layer  52  is adhered to or integrally formed with a flashlight lens cover  56 . In a reflective (front-lit) configuration in which the polarizing layer  42  is backed by a reflector, images are formed by light that transmits through both polarizing layers  42  and  52  (as regulated by addressable patterns within the LCD layer  44 ) en route to and from the reflector. The visual aid  50  could also be used in conjunction with a transmissive (backlit) LCD device. An outer polarizing layer (not shown) would be incorporated the modified LCD display  40  in place of the inner polarizing layer  42 , and the polarizing layer  52  of the visual aid  50  would replace the polarizing layer  42  for restoring functionality to the LCD display  40 . By shining light from the visual aid  50  on the back of the further modified display  40 , transmissions of light through the polarizing layer  52 , the addressable LCD layer  44 , and the substituted outer polarizing layer (not shown) form images apparent at the front of the display  40 . 
         [0025]      FIG. 5  illustrates another embodiment operating under similar principles. A device  60 , such as a PDA (personal digital assistant), incorporates a similar modified LCD display  40  and a separate polarizing layer  62 , which is removable at will. The polarizing layer  62  can be removed and replaced through a slot  64 , for example, whenever there is a need to view images with the LCD display  40 . The considered LCD display  40  can be a reflective (front-lit), a transmissive (backlit), or a transitional (hybrid) LCD display, and the replaceable polarizing layer  62  can be located on either side of the liquid crystal layer  44 . 
         [0026]    Polarizing layer  62  can also be a part of a separate handheld viewer or a part of a head-mounted viewer. For example, the polarizing layer  62  can be adhered to a lens or other optic or can be incorporated into a lens or other optic such as may be used for eyeglasses, orientable contact lenses, or other optical aids (e.g., sunglasses) with or without refractive power. 
         [0027]    All of the above devices can be arranged to support the selective viewing of information displayed on a LCD display  40 . Such selective viewing can be advantageous for security or privacy purposes. The LCD displays are missing a polarizing layer that can be supplied separately for enabling the displays. For purposes of security, the removal or omission of the inner polarizing layer adjacent to the backlit light source or front-lit reflective surface would be particularly effective because external polarizers would not reveal the image pattern encoded by relative rotations within the liquid crystal layer. A replacement polarizing layer is needed for straddling the liquid crystal layer in front of the light source or reflective surface. 
         [0028]    A secure ID card  70  as shown in  FIGS. 6 and 7  also exploits polarization effects for authenticating the secure card  70  in accordance with another embodiment of the invention. Operative layers of the card  70  can be sandwiched between front and back lamination layers  72  and  80 . At least one or both of the lamination layers  72  and  80  are preferably clear (transmissive) or at least translucent. However, one of the lamination layers e.g.,  72  can include a reflective surface so that light enters and exits the card  70  through the other lamination layer e.g.,  80 . For example, the lamination layers  72  and  80  can be made of glass or plastic. 
         [0029]    Printed layer  78  contains text and graphics along with a window  82  through which other layers of the card  70  are visible. Within the window, an image  84  is printed. A polarizing layer  76  beneath the printed layer substantially restricts the passage of light to a designated polarization, preferably an oriented linear polarization. A retarder layer  74  composed of variously shaped and oriented birefringent materials differentially affects the polar organization of light at different wavelengths. For producing latent images  86  in the form of text or graphics, the birefringent materials can be printed or cut out in different shapes and affixed in the same or different (e.g., mixed) orientations with respect to a birefringent axis of the films. One or more additional retarder layers (not shown) can be used to change the overall thickness of the birefringent films locally with respect to particular text or graphics  86  or more generally across a plurality of the text or graphics  86 . Such birefringent materials are available as conventional Mylar tapes and clear films that exhibit significant amounts of directional anisotropy. 
         [0030]    Shown in a location behind the secure ID card  70  is a polarized light source  88 , which can be in the form of a LCD display or a conventional light source together with a polarizer, such as the visual aid  50 . Starting with linearly polarized light from the polarized light source  88 , the retarder layer  74  locally converts the linearly polarized light into other polarization forms, such as circular or elliptical polarization. The polarization effects of the retarder layer  74  are preferably spectrally sensitive so that different visible wavelengths are affected differently. The resulting effect of the retarder layer  74  is either to allow light through the polarizing layer  76  that would otherwise not have passed or to attenuate light that would otherwise have passed through the polarizing layer  76 . With the polarization effects being wavelength sensitive, different colors of light are preferentially passed through the polarizing layer  76 , rendering the text or graphical forms within the retarder layer  74  visible at the surface of the secure card  70 . 
         [0031]    In place of or in addition to the laminating layer  72 , a reflective layer (not shown) can be affixed to the secure card  70  adjacent to the retarder layer  74 . Although additional intervening layers can be used, the intended optical pathway for viewing the latent images embedded in the alternative secure card involves light propagating through the polarizing layer  76  and the retarder layer  74 , reflecting from the reflective layer, and returning through the retarder layer  74  and the polarizing layer  76  for viewing. Any changes in the polarization of the light imparted by the retarder layer  74  differentially filter the light upon the second encounter with the polarizing layer  76 . 
         [0032]    A modified LCD computer display  90 , as shown in  FIG. 8 , includes a designated area  92 , which is modified by the removal of overlapping portions of an inner polarizer  94  and outer polarizer  98  that straddle an addressable liquid crystal layer  96  of the display  90 . A slot  100  provides access to the space evacuated by the removal of the overlapping portions of the inner and outer polarizers  94  and  98  within the designated area  92 . Although the liquid crystals of the liquid crystal layer  96  remain addressable with the designated area  92 , no images are formed within the designated area  92  because the light acted upon by the liquid crystals is unpolarized light. 
         [0033]    As shown in  FIG. 9A , a paired set of polarizers  102  and  104  are coupled together by a bow  106  and shaped in the form of blades for insertion through the slot  100  into the positions originally occupied by the removed portions of the inner and outer polarizers  94  and  98 . The polarization characteristics of the paired polarizer blades  102  and  104 , including the relative orientation of their polarization axes, are matched to the polarization characteristics of the inner and outer polarizers  94  and  98  of the display  90 . When inserted into position, straddling the liquid crystal layer  96  within the designated area  92 , the paired polarizer blades  102  and  104  contribute to forming images within the designated area  92 , thus restoring the display  90  close to its original operational form. Preferably, a computer controlled program places the secure information in the designated area  92  of the screen so as to hide the secure information until the paired polarizer blades  102  and  104  restore the display  90  to its operational form. 
         [0034]    The paired polarizer blades  102  and  104  can be uniquely shaped or supported by the bow  106 , which can also have a unique shape, and related to a corresponding unique shape of the slot  100  to limit insertion of the paired polarizer blades  102  and  104  to one or more designated displays. For example, bow  106  could be shaped to match a countersunk shape of the slot  100 . The mating shapes of the bow  106  and slot  100  could also be used to hide the presence of the bow  106 . The slot  100  could also be covered by door similar to the doors used for accessing DVDs and CDs. Entrance of the polarizer blades  102  and  104  into the slot  100  could be used to trigger a loading mechanism for moving the polarizer blades  102  and  104  into their operative position within the display  116 . Similar assistance could be used for removing the polarizer blades  102  and  104 . The triggering mechanism could also be made sensitive to one or more characteristics of the polarizer blades  102  and  104 , such as their shape, to deny access to blades not having the requisite characteristics. The two polarizer blades  102  and  104  supported by the bow  106  form a polar key that can be stored separately from the display  116  and maintained under the control of a user granted access to the secure information presented within the designated area  92  of the display  116 . 
         [0035]    Thus, access can be limited to information arranged for display  90  within the designated area  92  to the paired polarizer blades  102  and  104  and bow  106  that function as a key for unlocking information within the designated area  92 . Such key-type access could also be electronically controlled. For example, the bow  106  could be embedded with a key chip that must be sensed by the display  90  to permit access through the slot  100  for restoring function to the designated area  92  of the display  90 . 
         [0036]    Instead of removing portions of both the inner and outer polarizers  94  and  98  for temporarily disabling the designated area  92  of the display  90 , a portion of just one or the other of the inner and outer polarizers  94  and  98  could be removed. For example, a portion of just the inner polarizer  94  could be removed so that the front of the display is unaffected by the change. 
         [0037]    As shown in  FIG. 9B , just one of the polarizer blades  102 , which corresponds to the removed portion of the polarizer  94 , is mounted on the bow  106  for insertion through the slot  100  as a polar key for unlocking (i.e., revealing) information within the designated area  92 . The single polarizer blade design could also be adapted similar to the paired polarizer blade design to limit access into the display  116  to polarizer blades having the requisite characteristics. A similar electronic key function could also be incorporated into the bow  106  supporting the single polarizer blade  102  to provide an extra or alternative form of security. 
         [0038]    A product packaging  110 , as shown in  FIGS. 10 and 11 , incorporates a polarizer  112  within a hanging flap  114 . A video driven LCD display  116 , as shown in  FIG. 11 , is modified by the removal (or omission) of all or a portion of an outer polarizer adjacent to the front  118  of the LCD display  116 . The polarizer  112  preferably matches the outer polarizer removed from the LCD display  116 . For example, if the polarizer removed (or omitted) from the LCD display  116  is a linear polarizer, then the polarizer  112  is also preferably a linear polarizer with a similarly oriented polarization axis. However, the polar orientation of the polarizer  112  preferably differs from the customary polar orientation of polarized sunglasses, so that polarized sunglasses would not provide an appropriate substitute for the polarizer  112  to complete the LCD display  116 . 
         [0039]    Both the product packaging  110  with the polarizer  112  and the modified LCD display  116  are preferably located in or near a retail or promotional space  130  within which other similarly packaged products are on display for sale or promotion. The LCD display  116  preferably receives a video signal on an ongoing basis or in response to a sensor signal, such as a proximity sensor. Speakers, not shown, can also be used to broadcast an accompanying sound track. With the removal (or omission) of the display&#39;s front polarizer, no images appear within the modified display  116 . That is, even though image information is encoded within one of the polarizations emitted from the display  116 , the image information is largely obscured by a lack of contrast because of the presence of a complementarily encoded orthogonal polarization. As a result, the display  116  appears to emit light (e.g., white light) undifferentiated in color or intensity by the polarization effects of the liquid crystal layer. 
         [0040]    Directions  118  printed on the package  110  can be used to instruct the customer where and how to hold the package  110  in front of the display screen  116  to receive audio and video portions of the message. In accordance with these instructions, a customer can pick up the modified product packaging  110  and look through the polarizer  112  toward the display  116  to view the image information differentially encoded between polarizations. The polarizer  112  effectively completes the display  116  so that the contents of the display  116  are visible to the customer. Thus, the customer, while holding a product package  110  intended for sale, can be exposed to a marketing message optically encoded by the display  116  and revealed through the polarizer  112 , which completes the display  116 . Only customers holding packages incorporating the requisite polarizer  112  can view the message of the display  116 . 
         [0041]    Interactive features can be incorporated into a controller  120  for the display  116  supporting communications between the customer and a marketing program. For example, the display  116  could include a touch responsive screen to accept input from the customer and adjust the marketing message to the instant customer. 
         [0042]      FIG. 11  also shows an RFID tag  122  affixed to the package  110 . However, the RFID tag  122  or at least its RFID antenna is preferably mounted within the package  110  or embedded within or between layers of the package  110  so that the RFID antenna remains hidden and protected from abuse. The RFID tag  122  can be poled by an RFID reader  124  associated with the controller  120  to influence operation of the display  116  in response to the signal received by the reader  124 . For example, detection of the RFID tag  122  can be used as a trigger to turn on the display  116 , initiate a particular video message, or further cycle a video message. Differently encoded RFID tags  122  can be mounted within different product packages incorporating similar polarizers. The video messages can be adapted or completely changed to match the video messages to the different products. With a single or fewer displays than product types, a control algorithm can be used to play the video messages in a responsive order, such as by order of arrival of the RFID embedded packages within a prescribed zone near the LCD display  116 . The presence of more than one product of a type associated with a single message can be accommodated by cycling the same video message to assure that all customers holding the product view the entire message from start to finish. More than one message can be associated with the same product to maintain interest. In addition, more than one display can be mounted with the display or promotional area or different portions of the display  116  can be separately controlled to present different messages at once. 
         [0043]    Although the polarizer  112  is shown mounted within the window of a hanging flap  114  of the product package  110 , similar polarizers can be mounted on or otherwise incorporated into product packaging in other ways. Preferably, even if mounted flush to the package, the polarizer  112  can be reoriented as a working window for viewing the display  116  without significantly damaging the product packaging or becoming detached from the product packaging. Thus, the product packaging preferably remains in condition for sale despite being previously used by one or more customers for viewing the display  116 . In addition to mounting a polarizer in product packaging, the polarizer could be mounted in other branded items including advertizing material, other promotional items, including coupons, adjacent to a product display or other marketing center. The modified displays are also preferably located at or near the product displays or marketing centers within view of where customers pick of the modified product packaging or modified advertizing materials. 
         [0044]    While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as may be claimed.