Abstract:
A transit center apparatus is provided having one or more modules attachable to a transit stop pole to provide one or more of the following conveniences to a transit stop patron: information in an optionally illuminated modular display apparatus, overhead illumination, video camera surveillance, and wireless communication. These conveniences are preferably provided through an overhead assembly and a rugged information display case. The overhead assembly houses one or more of the group consisting of solar cells, a rechargeable battery pack, overhead lights, a cell phone antenna, camera, and related circuitry. The information display case provides backlighting and houses a switch assembly. The display case is preferably constructed from extruded, interlocking aluminum frame members and is easily installable on existing support poles.

Description:
RELATED APPLICATION INFORMATION 
   This Application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/388,532 entitled INFORMATION DISPLAY APPARATUS filed Jun. 13, 2002; and U.S. Provisional Patent Application Ser. No. 60/419,889 entitled TRANSPORTATION NOTIFICATION, EMERGENCY RESPONSE, AND SURVEILLANCE SYSTEM filed by Alan L. Bartlett on Oct. 21, 2002, both of which are herein incorporated by reference. 

   FIELD OF THE INVENTION 
   This invention relates to modules intended to provide conveniences to patrons at a transit node or center, such as a bus stop. More particularly, the present invention relates to one or more modules installed at a transit stop location that provide one or more of the following conveniences to a transit stop patron: information in an optionally illuminated modular display apparatus, overhead illumination, video camera surveillance, and wireless communication. 
   BACKGROUND 
   Public transportation is underutilized in many developed countries, especially the United States. Unattractive and poorly lit or unlit transit stops contribute to negative perceptions about public transportation in general. Thoughts of sitting on a bench in public in a bad part of town in the midst of strangers often provoke fears over personal safety. Lack of information regarding scheduled bus arrivals and drive-bys contribute to public frustrations over public transportation. Accordingly, there is a need for an attractive and economical transit center apparatus to increase community acceptance and ridership of public transportation. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention provides an apparatus for installation at a transportation or transit node (such as a bus stop, taxi cab pickup location, or any other pickup location for a transportation system). The apparatus comprises one or more modules attachable to a transit stop pole, shelter, or other support structure. The modules provide one or more of the following conveniences to a transit stop patron: information in an optionally illuminated modular display apparatus, overhead illumination, video camera surveillance, and wireless communication. 
   In one embodiment of the invention, a display apparatus is provided comprising one or more display panels and a plurality of interlocking extruded aluminum frame members adapted to wrap around a support member. A first interlocking frame member has a male connector and a second interlocking frame member has a corresponding female connector. The first interlocking frame member is adapted to interlock with the second interlocking frame member by inserting the male connector into the female connector. One or more of the plurality of interlocking frame members include compartments for holding the display panels. In one embodiment of the display apparatus, two of the interlocking frame members include compartments for holding the display panels. 
   The male and female connectors each have an elongate longitudinal dimension extending from a point at or near the top of the corresponding frame member to a point at or near the bottom of the corresponding frame member, so that the first interlocking frame member is adapted to be connected to the second interlocking frame member by sliding the male connector into the female connector along a longitudinal axis of the display apparatus. 
   The display apparatus also includes a support bracket dimensioned to partially wrap around, press against, and frictionally engage the support member when fastened to an interlocking frame member. The support bracket has a set of fastener passages dimensioned to align with another set of fastener passages in one of the interlocking frame member. A plurality of fasteners are inserted through these two sets of fastener passages to join the support bracket to the interlocking frame member in which said set of fastener passages is disposed. When fastened, movement of the display apparatus with respect to the support member is impeded. 
   The display apparatus further includes means for illuminating the display panels. In one embodiment, a plurality of parallel and linear channel grooves are disposed on a surface of the display panels. A process of scratching the display panel surface with a blade forms the channel grooves, which extend from the bottom to the top of the display panel. In particular, this groove-crating process is initiated at a first end of the display panel and terminated at the opposite end, so that the creation of each groove is initiated from the same first end. 
   In another embodiment, a pattern of regularly spaced thin parallel strips of light-diffusing material (such as ink or paint) is applied, via a silk-screen process, to the inside surface of the display panel. The strips extend from the top edge to the bottom edge of the display panel. 
   Another embodiment of the invention comprises a post; an overhead assembly mounted on the post; one or more light emitters mounted within the overhead assembly and oriented to project the emitted light toward the ground in the immediate vicinity of the transit stop apparatus; a rechargeable battery; a solar energy collector; a user-operated switch mounted on the post that enables a user to activate the light emitters; and electrical circuitry connecting the solar energy connector, switch, the rechargeable battery, and the light emitters in a manner adapted to allow the light emitters to be turned on upon user activation of the switch and to allow the solar energy collector to recharge the battery. This embodiment optionally also comprises a light control circuit operatively connected to the switch, battery, and light emitters, and programmed to turn off the light emitters after a finite period of illumination has elapsed. In another optional feature of this embodiment, the light control circuit detects ambient illumination from the solar energy connector and prevents activation of the light emitters when the ambient illumination exceeds a predetermined threshold. 
   This embodiment optionally, but not necessarily, also includes a display panel mounted on the post, the display panel being adapted to provide transportation-related information to persons at the transit stop; a second set of one or more light emitters mounted inside the display panel and oriented to illuminate the display panel; and a display light activation switch; wherein the switches are mounted on the display panel and wherein the electrical circuitry connects the display light activation switch, the second light emitter set, and the rechargeable battery in a manner adapted to turn on the second light emitter set and thereby illuminate the display panel. 
   The embodiment alternatively or optionally additionally includes a flashing light switch mounted on the post; and a light control circuit programmed to flash the light emitters on and off repeatedly for a finite period of time; wherein the electrical circuitry connects the flashing light switch, the light control circuit, and the light emitters in a manner adapted to cause the light emitters to be flashed on and off upon user activation of the flashing light switch. 
   The embodiment alternatively includes a transportation driver signaling switch mounted on the post and a transportation signaling transmitter operable to broadcast an invisible wireless signal to a receiver (such as a pager) mounted on a transportation vehicle, wherein the electrical circuitry connects the transportation driver signaling switch with the transportation signaling transmitter to enable a user to transmit a signal to a driver of a transportation vehicle and thereby alert the driver that the user is waiting to be picked up. 
   The embodiment alternatively or optionally additionally includes a wireless two-way voice transceiver; an antenna for receiving and transmitting signals to and from the transceiver; and a communication link switch mounted on the post that enables a user to activate the wireless two-way voice transmitter and receiver; wherein the electrical circuitry connects the rechargeable battery, transceiver, communication link switch, and antenna in a manner adapted to enable two-way communication upon user activation of the communication link switch. 
   Yet another embodiment of the invention comprises a post; an overhead assembly mounted on an upper portion of the post; a display assembly mounted on the post below the overhead assembly, the display assembly providing a display surface for displaying information; at least one light emitter mounted on the display assembly and oriented to cast light upon the display surface of the display assembly; a rechargeable battery operable to provide power to the at least one light emitter; a solar panel mounted on the overhead assembly operable to recharge the battery; and electrical circuitry connecting the solar panel, rechargeable battery, and light emitter in a manner adapted to enable illumination of the display panel. 
   This alternative embodiment preferably further comprises a transparent display panel having an inside surface and an outside surface, the transparent display panel being mounted in the display assembly, and a thin, light-diffusing translucent sheet with printed information, the translucent sheet overlaying the outside surface of the transparent display panel; wherein the at least one light emitter is oriented along an edge of the display panel to project light into the transparent display panel. Furthermore, it is preferred for the transparent display panel to have highly polished top and bottom edges. Furthermore, it is preferred that a pattern of regularly spaced thin parallel strips of light-reflecting material be affixed to the inside surface of the display panel and extend between the top and bottom edges of the display panel. 
   This alternative embodiment preferably further comprises a second set of light emitters mounted within the overhead assembly and oriented to project the emitted light toward the ground in the immediate vicinity of the transit stop apparatus and a user-operated switch mounted on the display panel that enables a user to activate the second set of light emitters; wherein the electrical circuitry also connects the rechargeable battery, the second set of light emitters, and the user-operated switch in a manner adapted to allow the second set of light emitters to be turned on upon user activation of the switch. 
   This alternative embodiment optionally also comprises a second user-operated switch mounted on the display assembly; and a light control circuit programmed to flash the second set of light emitters on and off repeatedly for a finite period of time; wherein the electrical circuitry connects the second user-operated switch, the light control circuit, and the second set of light emitters in a manner adapted to cause the light emitters to be flashed on and off upon user activation of the second user-operated switch. 
   This alternative embodiment also optionally comprises a transportation signaling device mounted in the overhead apparatus and operable to provide a signal to a driver of a transportation vehicle and a user-operated switch mounted on the display apparatus; wherein the electrical circuitry connects the user-operated switch with the transportation signaling device to enable a user to alert a driver of a transportation vehicle that the user is waiting to be picked up. 
   The alternative embodiment also optionally comprises a camera mounted in the overhead assembly and operable to capture images of the area below the overhead assembly and in the immediate vicinity of the transit stop apparatus and a wireless communication circuit coupled to the camera and operable to transmit images captured by the camera. 
   These and other aspects, features, and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheets of drawings, which illustrate the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of one embodiment of a single-sided display case built in accordance with the present invention. 
       FIG. 2  is a front-end view of the single-sided display case of  FIG. 1 . 
       FIG. 3  is a side view of the single-sided display case of  FIG. 1 . 
       FIG. 4  is a rear-end view of the single-sided display case of  FIG. 1 . 
       FIG. 5  is a top-end view of the single-sided display case of  FIG. 1 . 
       FIG. 6  is an exploded perspective view of the single-sided display case of  FIG. 1 . 
       FIG. 7  is a perspective view of the sign body frame member of the single-sided display case of  FIG. 1 . 
       FIG. 8  is a cross-section of the sign body frame member of  FIG. 7 . 
       FIG. 9  is a perspective view of the back cover frame member of the single-sided display case of  FIG. 1 . 
       FIG. 10  is a cross-section of the back cover frame member of  FIG. 9 . 
       FIG. 11  is a perspective view of the lid of the single-sided display case of  FIG. 1 . 
       FIG. 12  is a cross-sectional side view of the lid of  FIG. 11 . 
       FIG. 13A  is a perspective view of the bottom cover of the single-sided display case of  FIG. 1 . 
       FIG. 13B  is a top view of the bottom cover of  FIG. 13A . 
       FIG. 14  is a perspective view of the support bracket of the single-sided display case of  FIG. 1 . 
       FIG. 15  is a cross section of the support bracket of  FIG. 14 . 
       FIG. 16  is a front-end view of another embodiment of the single-sided display case built in accordance with the present invention. 
       FIG. 17  is a perspective view of the bottom cover of the single-sided display case of  FIG. 16 , including push button holes. 
       FIG. 18  is a perspective view of one embodiment of a double-sided display case built in accordance with the present invention. 
       FIG. 19  is an exploded view of the double-sided display case of  FIG. 18 . 
       FIG. 20  is a side view of the double-sided display case of  FIG. 18 . 
       FIG. 21  is a top-end view of the double-sided display case of  FIG. 17 . 
       FIG. 22  is a cross-sectional end view of one the interlocking side frame member of the double-sided case of  FIG. 17 . 
       FIG. 23  is a partial cross-sectional view of one embodiment of an edge-lit display panel built in accordance with the present invention. 
       FIG. 24  is an elevated perspective view of one embodiment of a transportation node apparatus comprising an information display assembly and an overhead light assembly. 
       FIG. 25  is a bottom-up perspective view of the transportation node apparatus of  FIG. 24 . 
       FIG. 26  is an elevated frontal perspective view of the overhead light assembly of  FIG. 24 . 
       FIG. 27  is a posterior perspective view of the overhead light assembly of  FIG. 26 . 
       FIG. 28  is a bottom-up frontal perspective view of the overhead light assembly of  FIG. 26 . 
       FIG. 29  is an exploded view of the overhead light assembly of  FIG. 26 . 
       FIG. 30  is another exploded view of the overhead light assembly of  FIG. 26 . 
       FIG. 31  is a perspective view of a face plate for an information display assembly comprising cell phone capabilities. 
       FIG. 32  is a frontal view of the face plate of  FIG. 31  superimposed with exemplary labeling. 
       FIG. 33  is a cross sectional side view of  FIG. 31 . 
       FIG. 33A  is an exploded perspective view of the face plate of  FIG. 31  in relation to the display panel edge lights, edge light bracket, and the display assembly. 
       FIG. 34  depicts a flow chart of one embodiment of an emergency response system and method for use with the present invention. 
       FIG. 35  is a schematic diagram of one embodiment of a transportation node apparatus providing a backlit information display, overhead illumination, security camera, and cell phone communications. 
   

   DETAILED DESCRIPTION 
   Co-pending U.S. application Ser. No. 09/867,143, filed May 29, 2001, for a rotating information display case, provides one embodiment of an information display apparatus that addresses the need for an aesthetically pleasing and multi-functional display information display apparatus that can be readily installed on existing supports. This application describes several alternative embodiments that address many of the same needs. It will be understood that many of the aspects and features of U.S. application Ser. No. 09/867,143 may be combined with the aspects and features described below, even if not specifically described herein. Accordingly, that application is herein incorporated by reference for all purposes. 
   Based on the description and illustrations provided herein, the many benefits provided by the invented structure and methods of utilization are apparent. These described benefits, as well as those that are inherent to those skilled in the art, fall within the scope of the invention of the present patent application as limited only by the claims appended hereto. 
     FIGS. 1–17  illustrate several embodiments of a single-sided information display assembly or display case  100  designed and assembled in accordance with the present invention. Display assembly  100  comprises two interlocking frame members  110  and  120 , a display panel  130 , a window panel  140 , two support brackets  150 , a bottom cover  160 , and a top plate or lid  170 . 
   Front frame member  110 , shown in greatest detail in  FIGS. 7–8 , comprises a substantially planar back portion  810  and two integral and substantially planar side walls  830 ,  850  extending at right angles from the longitudinal edges of back portion  810 . Two flanges  832 ,  834 , each approximately ⅛ inch thick and extending along most of the length of frame member  110 , project inwardly from the sidewall  830 , parallel to the back portion  810 , for a distance of about ¼ inch. Likewise, two similarly dimensioned flanges  852 ,  854  opposite flanges  832 ,  834  project inwardly from sidewall  850 . A gap or window compartment  870  of approximately 0.177 inches exists between the flanges  832  and  834 , and likewise, between  852  and  854 , for inserting the window panel  140 . Another gap or display compartment  880  of approximately 0.41 inches exists between the flanges  834  and  854  and the back portion  810  for inserting the display panel  130  and display graphics. 
   Two semi-cylindrical knob-like male connectors  812 ,  814  project outwardly from the planar back portion  810 . The knob-like portion of the connectors  812 ,  814  have a radius of approximately 0.085 inches. Connectors  812 ,  814  preferably extend along most of the length (i.e., from about one inch from the top to about one inch from the bottom) of the frame member  110 . The planar sided portions  830 ,  850  also include aesthetically pleasing grooves  836 ,  856  extending along the length of frame member  110 . 
   Rear interlocking frame member  120 , shown in greatest detail in  FIGS. 9–10 , comprises one or more surface portions  1020 ,  1030 , and  1040  configured to engage corresponding surface portions of a support member or post  190 . Rear interlocking frame member  120  also comprises side extensions  1050  and  1060  adapted to reach around the sides of support  190  and engage the back portion  810  of the front frame member  110 . Two female socket connectors  1012 ,  1014  project inwardly from the side extensions  1050  and  1060 . Connectors  1012 ,  1014  extend along the entire length (i.e., from top to bottom) of the rear frame member  120 . The connectors  1012 ,  1014  are dimensioned and shaped to interlock with the front frame member&#39;s male connectors  812 ,  814 . In particular, the semi-cylindrical apertures formed within connectors  1012 ,  1014  have radii of approximately 0.105 inches. This interlocking assembly enables frame members  110  and  120  to be fastened together to form a durable and strong self-supporting assembly. 
   In a preferred embodiment, interlocking frame members  110  and  120  are formed of extruded aluminum, in particular,  6061 -T 3  extruded aluminum. While such materials are presently preferred because of their cost, durability, and other characteristics, other fabrication materials, such as extruded plastics, can be used without deviating from the full scope of the present invention. 
   Interlocking frame members  110  and  120  can be fashioned to have any suitable length or width. When used as bus stop displays, frame members  110  and  120  have a preferred length of about 2 feet and a preferred width of between about 3½ inches, particularly for narrow support members  190 , and 6 inches, which is suitable for wider support members  190  or for displaying greater amounts of information. A narrow and relatively slim sign profile is preferred so that the display apparatuses  100  minimally obstruct the view of the surrounding environment and to minimize dangers to pedestrians in high-traffic areas. 
   The display panel  130  provides the surface for displaying information. When inserted in the front frame member  110 , the display panel  130  is secured by and between flange members  834  and  854  and the back portion  810 . In one embodiment, the display panel  130  comprises a relatively stiff base material, such as cardboard or white polyvinyl chloride (PCV) plastic, on which the information to be displayed is printed or overlaid. For non-illuminated display panels  130 , PCV white is preferred because it functions as a background color for transparent graphics. 
   In another embodiment, described in detail in connection with  FIG. 23  below, the display panel  130  comprises an illuminated glassy thermoplastic, such as an edge-lit acrylic, affixed to or overlaid by a waterproof light-diffusing paper on which the information is printed. In yet another embodiment, the surface of display panel  130  includes a photoluminescent material that illuminates the display for night viewing, such as the materials described in U.S. Pat. No. 6,395,408 to Nelson, U.S. Pat. No. 6,364,498 to Burbank, and U.S. Pat. No. 6,207,077 to Burnell-Jones, all of which are herein incorporated by reference. A photoluminescent material suitable for use with the present invention is DALITE-50™, which is sold by Datrex located in Kinder, La. The DALITE-50™ material is comprised of flexible laminated film coated with permanent acrylic pressure sensitive adhesive and backed with poly-coated release liner. This photoluminescent material is advertised to glow for as long as 24 hours. Other panel materials suitable for use with the present invention, and well known in the art, include those materials providing frosted, clear, or translucent white panels. 
   The window panel  140  is preferably comprised of polycarbonate material or tempered glass. It is preferable to utilize a material that is less likely to break or shatter because of its use in public. When inserted in the front frame member  110 , the window panel  140  is secured by and between flange members  832 ,  834 ,  852  and  854 . The window panel  140  may also include Braille lettering to enable sight impaired sign users to better navigate the routes on which the sign is placed. 
   The window panel  140  is preferably of a length slightly less than that of the front frame member  110 . Therefore, when the window panel  140  is installed in the frame member  110 , a ventilation port is formed between the top edge  148  of the window panel  140  and the inside planar surface  178  of top plate  170 . It will be observed when the display apparatus  100  is fully assembled, flanges  834  and  854  create a display cavity  875  approximately ⅛ of an inch in depth between the window panel  140  and display panel  130 . The ventilation port, which is in fluid communication with the display cavity  875 , facilitates convection venting of the display cavity  875  to prevent fogging of the inside surface of window panel  140 . Ventilation is further aided by ventilation slots  163  and  164  in the bottom cover  160  of the display apparatus  100 , which is described in greater detail below in connection with  FIG. 13 . 
   The support brackets  150 , shown in greatest detail in  FIGS. 14–15 , function as internal friction clamps to mount the rear interlocking frame member  120  to the support member  190 . The support bracket  150  includes one or more substantially planar portions  151 ,  152  and  153  configured to engage one or more corresponding surface portions of support member  190 . The support bracket  150  also includes two end portions  154 ,  155  each having a fastener passage  156 ,  157 . The rear interlocking frame member  120  has corresponding fastener passages  126 ,  127 . To secure the support bracket  150  to the frame member  120 , fasteners  124 , preferably clamp bolts, are inserted through the support bracket&#39;s fastener passages  156 ,  157  and through the rear interlocking frame member&#39;s corresponding fastener passages  126 ,  127 . In this manner, the display apparatus  100  is installable on an existing support member  190  and supportable by frictional engagement, eliminating any need to drill holes into the existing support member  190 . 
   In one embodiment of the present invention, the support brackets  150  are configured to deform the rear interlocking frame member  120  when tightened against the support member  190 . The deformation is significant enough to prevent disengagement of the front interlocking frame member  110  from the rear interlocking frame member  120 . Accordingly, in this embodiment it is important, before installing the front interlocking frame member  110  onto the rear interlocking frame member  120 , to refrain from over-tightening the fasteners  124 . Of course, the fasteners  124  should be tightened after the front interlocking frame member  110  has been installed to prevent its disengagement from the rear interlocking frame member  120 , as well as to prevent vertical movement of the display apparatus  100  with respect to the support member  190 . 
   Support brackets  150  are preferably fabricated from sheet steel. However, other materials may be used without deviating from the scope of the invention. For example, the support brackets  150  can be fabricated from plastic, nylon, or other like material. 
   The bottom cover  160  ( FIG. 13 ) is secured to the rear interlocking frame member  120  via fasteners  164 ,  165 , preferably self-tapping screws, which are inserted through mounting holes  161 ,  162  to engage the bottom of female connectors  1012 ,  1014 .  FIGS. 16–17  illustrate an alternative bottom cover  1700  embodiment for the display assembly  100 . Cover  1700  includes one or more apertures  1710 ,  1720 ,  1730  to provide access to touch sensitive buttons that are optionally used to control the lighting systems or other electronic functions (not shown) of the display apparatus  100 . For example, a first button may be used to provide backlighting for the display. A second button may be used to turn on environmental lighting for the area around the display. A third button might be used to turn on an alarm. Moreover, Braille lettering can be incorporated on the buttons or bottom cover  1700  to enable sight impaired sign users to utilize the buttons. 
   In one embodiment, one of the buttons operates a flashing signal to notify an approaching bus driver that there are people waiting to board the bus, such as described in U.S. Pat. No. 6,355,989 entitled “Public transportation signaling device” to Westcott, which is herein incorporated by reference. In a more preferable embodiment, other means, more sophisticated than a flashing light, and not comprehended within the disclosure of U.S. Pat. No. 6,355,989, are used to notify an approaching bus driver that there are people waiting to board the bus. For example, one of the buttons may cause a wireless signal to be transmitted to a receiving device, such as a pager, on board an approaching bus to notify the bus driver that patrons are waiting. Advantageously, a wireless signaling device, unlike the flashing light of U.S. Pat. No. 6,355,989, is easily detected during the day as well as night. 
   Bottom covers  160  and  1700  preferably include one or more ventilation slots  163 ,  164  that function, in conjunction with the ventilation port between the top edge  148  of window panel  140 , to convect air through and transmit vapor away from the display cavity  875  between the display and window panels  130  and  140 . Means are thereby provided for transmitting vapor out of the display cavity  875  that would otherwise fog the display panel  130  and/or window panel  140  and prevent proper use of the display apparatus  100 . 
   The removable top plate or lid  170  ( FIGS. 11–12 ) provides access to the graphics of display apparatus  100 . Two guide pins  176 ,  177  protrude downwardly from the removable top plate  170  to engage the female connectors  1012 ,  1014  and keep the top plate  170  rigid and straight with respect to the front interlocking frame member  110 . Additionally, a fastener, such as a conventional key-operated lock  172  with a tab  173 , is provided to prevent unauthorized access to the display apparatus&#39;s graphics. As shown in  FIG. 7 , a slot  813  is provided to engage the tab  173  of the top plate&#39;s lock  172 . A suitable lock for use with the illustrated embodiment is manufactured by the Illinois Lock Company of Wheeling, Ill., and identified by part number BC520S-VA-KA-0406/0425-N-K1. This particular brass-plated lock suitable for harsh weather environments. 
   The removable top plate or lid  170  also includes a downwardly extending lip  175  to shield the ventilation port between the top edge  148  of window panel  140  and the inside planar surface  178  of the top plate  170  from the elements. Incidentally, the top plate  170  and bottom cover  160  or  1700  are preferably made of  5052  aluminum sheet metal, although many other suitable materials are available. 
   Changing out a display panel  130  or window panel  140  merely requires removal of the top plate  170 . After removing the top plate  170 , the display panel  130  or window panel  140  is simply lifted up and away from the display assembly  100 . Replacing a display panel  130  or window panel  140  merely requires the reverse of removing the display panel  130  or window panel  140 . 
   In a preferred embodiment, support member  190  comprises an octagonal shaped sign post described in U.S. Pat. No. 5,848,502 and illustrated in Design Patent 415,847, both to Schaefer, both of which are herein incorporated by reference. Such posts, having about a 2-inch diameter, can be obtained from the assignee-at-issue of those patents, S-Square Tube Products of Commerce City, Colo. Such support members  190  are preferred because of their aesthetic qualities as well as their resistance to rotation, torsional strength, tamper resistant construction, and ease of installation and/or replacement. Such support members  190  are also preferred, when uniquely used throughout a locality for the locality&#39;s bus stops, because their undulating surface geometry conveniently enables sight-impaired individuals to identify the locality&#39;s bus stops. Nevertheless, it will be appreciated that the display assembly  100  is compatible for mounting on a wide variety of sign posts and support members. It will also be appreciated that with minor adaptations of the geometric and/or structural configuration of one or more of the interlocking frame members  110 ,  120 , support brackets  150 , lid  170 , and bottom cover  160 , display assembly  100  will be compatible with an even wider variety of support members. 
   In operation, the display apparatus  100  is installed onto an existing support member  190  by loosely securing the rear frame member  120  to the support brackets  150  using the appropriate fasteners  124 . Next, the bottom cover  160  or  1700  is affixed to the front frame member  110  via self-tapping screws  164 ,  165  that are screwed into the bottom ends of female connectors  1012 ,  1014 . Then, the front frame member  110  is slidably mated with the rear frame member  120  by inserting the male connectors  812 ,  814  into the female connectors  1012 ,  1014 . Then, fasteners  124  are tightened to prevent further lateral movement of the front frame member  110  with respect to rear frame member  120 . Next, the display and window panels  130  and  140  are installed in the front frame member  110 . Finally, top cover  170  is placed on top of the interlocking frame members  110  and  120 , so that guide pins  176 ,  177  of the top cover  170  penetrate into the top ends of female connectors  1012 ,  1014 . The top cover  170  is finally secured be engaging the lock mechanism  172  so that tab  173  penetrates slot  813 . It should be appreciated that some of these steps can be performed in a different order without departing from the scope of the present invention. 
     FIGS. 18–22  illustrate one embodiment of a double-sided information display assembly or case  200  designed and assembled in accordance with the present invention. Display assembly  200  comprises two interlocking main frame members  210 , two interlocking side frame members  220 , two display panels  230 , two window panels  240 , four support brackets  250 , two bottom covers  260 , and two top plates or lids  270 . The two interlocking main frame members  210  are dimensioned and configured like the interlocking front frame member  110  described in connection with  FIGS. 7–8 . Likewise, the display panels  230  and window panels  240  are of the same type as described in connection with the display panel  130  and window panel  140  described above. 
   Interlocking side frame member  220 , shown in greatest detail in  FIGS. 19 and 22 , comprises several planar portions  221 ,  222 ,  223 , and  224  joined together in a manner forming two ridges separated by a groove. Adjoining planar portions  221  and  222  intersect to form a first ridge. Adjoining planar portions  223  and  224  intersect to form a second ridge. In between the two ridges, adjoining planar portions  222  and  223  intersect to form the groove. 
   Two female socket connectors  2012 ,  2014  project inwardly from the planar portions  221 ,  224 . Connectors  2012 ,  2014  extend along the entire length (i.e., from top to bottom) of the side frame member  220 . The connectors  2012 ,  2014  are dimensioned and shaped to interlock with the main frame member&#39;s male connectors (cf.  812 ,  814  of  FIG. 8 ). In particular, the semi-cylindrical aperture formed within connectors  2012 ,  2014  has a radius of approximately 0.105 inches. This interlocking assembly enables frame members  210  and  220  to be fastened together to form a durable and strong self-supporting assembly. 
   The planar portions  223  and  224  of the side members  220  include fastener passages  226  and  227  for mounting the support brackets  250 . Planar portions  223  and  224  are urged toward each other when the support brackets  250  wrapping around the support member  190  are mounted to the side frame members  220  and the fasteners securing the support brackets  250  are tightened. It should be noted that in the preferred embodiment, the tightening of such fasteners deforms the side frame members  220 , including female connectors  2012  and  2014 , enough to prevent disengagement of the main frame members  210  from the side frame member  220 . Accordingly, in this embodiment it is important, before installing the main frame members  210  onto the side frame members  220 , to refrain from over-tightening the fasteners. Of course, the fasteners  124  should be tightened after the main frame members  210  have been installed to prevent their disengagement from the side frame members  220 . 
   In operation, the display apparatus  200  is installed onto an existing support member  190  by loosely securing the side frame members  220  to the support brackets  250  using appropriate fasteners inserted through fastener passages  256 ,  257  and corresponding fastener passages  226 ,  227 . Next, the bottom covers  260  (or covers similar to the bottom covers  1700  shown in  FIG. 17 ) are affixed to the main frame members  210  via self-tapping screws that are screwed into the bottom ends of female connectors  2012 ,  2014 . Then, the main frame members  210  are slidably mated with the side frame members  220  by inserting the male connectors (cf.  812 ,  814  of  FIG. 8 ) into the female connectors  2012 ,  2014 . Next, the fasteners are tightened to prevent further lateral movement of the display apparatus  200  with respect to supporting member  190  and prevent lateral movement of the main frame members  210  with respect to side frame members  220 . Then, the display and window panels  230  and  240  are installed in the main frame members  210 . Finally, top covers  270  are placed on top of the interlocking frame members  210  and  220 , so that guide pins (not shown) of the top covers  270  penetrate into the top ends of female connectors  2012 ,  2014 . The top covers  270  are finally secured by engaging lock mechanisms  272  each having a tab  273  that penetrates a slot  823  of the corresponding main frame member  210 . It should be appreciated that some of these steps can be performed in a different order without departing from the scope of the present invention. 
   A preferred embodiment of the present invention provides backlighting to the display panel  130 . There are, of course, a variety of ways to backlight the display panel  130 , some of which are described in U.S. application Ser. No. 09/867,143. One of the challenges involved in backlighting displays, and particularly edge-lit displays, is illuminating the displays evenly. This application discloses several novel and non-obvious embodiments to meet that challenge. 
   The presently most preferred embodiment for providing evenly diffused and adequate illumination is to obtain a display panel  130  comprised of a low-cost glassy thermoplastic such as acrylic or Plexiglas® having a preferred width of between 0.1 inches and the width of the display compartment  880 , more preferably about ⅜ of an inch. Long, thin parallel strips of light-diffusing, light-reflecting, or opaque material, extending longitudinally along the length of the display panel  130 , are affixed to the inside (i.e., back) surface of display panel  130 . Each strip  130  has a preferable width of about 0.01 to 0.05 inches, more preferably about 0.03 inches. Moreover, the strips are preferably spaced about 0.05 to 0.2 inches apart, more preferably about 0.15 inches apart. Alternatively, the paint, ink or other opaque, light-diffusing, or light-reflecting material is applied to the display panel sufficient to cover approximately 10–30% of the inside surface of display panel  130 , more preferably about 20% to 28% for a display panel that is about 2 feet long by 3⅜ inches wide. Furthermore, we have found that the longer the display panel  130 , the smaller the ratio of paint coverage desired. Too much or too little coverage results in uneven lighting along the length of the display panel  130 . 
   The display panel&#39;s edges, particularly the top and bottom edges, are preferably well polished so that when light is introduced into the display panel  130  through its top or bottom edge or both the top and bottom edges, a substantial portion of the light is reflected back into the panel  130  when the light reaches the opposite side(s). 
   The opaque material preferably comprises paint or glossy epoxy ink, but could alternatively comprise an adhesive. Preferably, the paint or ink is inexpensively applied to the inside surface of the display panel  130  using a reusable mask such as a silk screen. The mask or silk screen may be generated by drafting a mask design having the desired pin stripe dimensions on a computer, printing the mask design onto clear vinyl acetate board, stretching a piece of silk screen material tightly over a frame, placing the vinyl acetate board underneath and in contact with the silk screen material, dressing the silk screen with chemicals selected by one of ordinary skill in the art of silk screening, and applying intense light or heat to generate a chemical reaction to “burn in” the design from the vinyl acetate board into the silk screen. Thereafter, the silk screen is placed in contact with the display panel  130  and paint or ink is applied (e.g., by injection, spreading or scraping) to the silk screen. Where the artwork has been burned into the silk screen, paint or ink flows freely through the silk screen and onto the display panel  130 . 
   A glossy backer, such as a bright white vinyl panel or board or glossy piece of paper, is placed in contact with the inside (i.e., back surface) of the display panel  130 . The display graphics itself (e.g., a bus schedule) should be comprised of a thin translucent film or paper (not shown) such as vellum, which functions to diffuse the light. The display graphics should be placed in contact with the outside (i.e., front) surface of the display panel  130 . The display panel  130 , glossy backer, and display graphics are placed in the front interlocking frame member  110  between the flanges  834 ,  854  and the back portion  810 . When installed, the striped surface of the display panel  130  should face the back portion  810 , and the display graphics should face the display panel  140 . 
   It is believed that this light-diffusing invention would be suitable for any back-lit display, including standard picture frames. For example, light emitting devices, such as LEDs, could be arranged in one or more edges of a picture frame having a display panel meeting the description above. 
     FIG. 23  illustrates a partial cross section of yet another embodiment of an edge-lit display panel  2300  built for use with the display apparatus of the present invention. The display panel  2300  is made of low-cost glassy thermoplastic such as acrylic or Plexiglas® having a preferred width of between 0.1 inches and the width of the display compartment  880 , more preferably about ⅜ of an inch. The inside surface of display panel  2300  preferably includes several linear, parallel channel grooves or scratches  2320  extending longitudinally along the length of the window panel. Each groove  2320  has a preferable depth and width of about 0.01 to 0.05 inches, more preferably about 0.02 inches. Moreover, the grooves are preferably spaced about 0.05 to 0.2 inches apart, more preferably about 0.1 inches apart. Although not shown, the window panel&#39;s edges are preferably well polished so that when light is introduced into the window panel, a substantial portion of it is reflected back into the window when the light reaches the panel&#39;s edges. 
   The display panel&#39;s grooves  2320  may be formed in any suitable way, for example, through etching or molding. In one preferred embodiment, each of the window panel&#39;s grooves  2320  are formed by running a precision knife or utility blade across the length of the window panel. Even more preferably, each groove  2320  is formed by passing the knife in a single direction. Lights (not shown), such as high-efficiency white light emitting diodes, are placed near the bottom of interlocking frame member  110 , adjacent the back portion  810 , to introduce visible light into the display panel  2300  through the display panel&#39;s bottom edge. A portion of the light is then reflected back and forth between the edges of the display panel  2300 . Another portion of the light escapes through grooves  2320  to evenly illuminate the display graphics. 
   A glossy piece of paper (not shown) should be placed in contact with the grooved surface of the display panel  2300 . The display graphics itself (e.g., a bus schedule) should be comprised of a thin translucent film or paper (not shown) such as vellum which functions to diffuse the light. The display graphics should be placed in contact with the surface opposite the grooved surface of the display panel  2300 . The display panel  2300 , glossy backer, and display graphics are placed in the front interlocking frame member  110  between the flanges  834 ,  854  and the back portion  810 . When installed, the grooved surface of the display panel  2300  should face the back portion  810 , and the display graphics should face the display panel  140 . The display panel  2300  is also preferably installed so that the direction in which the grooves  2320  were cut tends away from the illuminating light source. 
   Yet another edge-lighting, light diffusing embodiment uses a reflective film as a backing to an acrylic panel on which a clear or translucent display graphic is mounted. For example,  3 M markets a reflective film product under the trademark Scotchlite™, which contains small reflectorized elements to make graphics highly visible at nighttime by reflected light. The reflective film is fairly effective in evenly illuminating the display when edge light sources are used to introduce light into the acrylic panel. 
   Yet another embodiment for an edge-lighted display utilizes a thermoplastic material, such as acrylic, interspersed with a light-diffusing additive. A potentially suitable light-diffusing acrylic material is marketed under the trademark ELiT™. 
   Yet another embodiment for backlighting utilizes a photoluminescent material that is charged by sunlight and which can glow for up to eight hours at night. Whether used in combination with or as an alternative to edge lighting, the luminescent backer embodiment advantageously yields energy savings. 
     FIGS. 24–30  depict additional embodiments of a transportation node apparatus  300  comprising a user-operated overhead assembly or module  310 .  FIGS. 24–25 , in particular, depict a transportation node apparatus  300  comprising an information display assembly  100  in combination with an overhead assembly  310 .  FIGS. 26–30  provide additional views of the overhead light assembly  310 . 
   In a preferred embodiment, the overhead assembly  310  provides overhead illumination to cast an arc of light onto the ground, and any structures such as benches superimposed thereon, below. The overhead assembly  310  may optionally also, or in the alternative, provide overhead video or still-frame camera surveillance to increase transportation patron security. 
   As shown in  FIGS. 24–30 , the overhead assembly  310  comprises a main housing  352  and a lid  354 . Main housing  352  is frictionally mounted to the support member  190  with a pole clamp  356  and two screws  357 . The lid  354  fits over lip  353  of main housing  352  and is held in place, but removably so, by screws  351 . 
   The main housing  352  provides space for a power supply  358 , lights  340 , which preferably comprise efficient and durable high intensity light emitting diodes (LEDs), and an optional protective lens  345 . The power supply  358  preferably comprises a rechargeable battery pack. Solar panels  315  may be affixed to the lid  354 . A circuit board  360  is provided to, among other optional functions, enable or disable the lights  340  and the recharging of the power supply  358 . 
   In the advanced embodiment depicted in  FIGS. 24–30 , the overhead assembly  310  provides not only downlighting, but also camera surveillance and a communications antenna  330 . A camera  320  covered by a semispherical protective guard  325  enables still frames or motion video of the scene below to be captured. The circuit board  360  also controls the operation of the camera  320 . 
   It will be understood that just as the present invention is broad enough to extend to transportation node apparatuses covering only the claimed display apparatus, it is also broad enough to extend to transportation node apparatuses comprising a user-operated overhead assembly or module  310  that provides only one, or a subcombination, of these conveniences. 
     FIGS. 31–33A  depict an embodiment of a face plate  3100  for use with the display assembly  100  comprising cell phone capabilities. Face plate  3100  preferably substitutes for the bottom cover  1700  depicted in  FIGS. 16–17 . Face plate  3100  provides one or more apertures  3115 ,  3125 ,  3135 , and  3145  through which touch sensitive buttons  3110 ,  3120 ,  3130 , and  3140  protrude. 
   As suggested in connection with  FIGS. 16–17 , one of the buttons  3110 ,  3120  and  3130  is preferably used to illuminate the display for a predetermined period of time such as 30 seconds. A second button is preferably used to illuminate the environment, or, more particularly, to activate the overhead lighting of the overhead assembly  310 . A third button, if provided, may be used for any intended purpose. In one embodiment, a third button is used to activate circuitry providing an audible report of the expected time-to-arrival of the next bus for each of the bus routes serving the bus stop. In another embodiment, the third button causes the overhead illumination to flash on and off. In yet another embodiment, the third button transmits a signal to an approaching bus driver or to a centralized dispatch system that a patron is waiting to be picked up. Such a signal may comprise a light pointed in the direction of an approaching driver. More preferably, such a signal would comprise a wireless signal to activate a receiver, such as a paging device, in a nearby transit vehicle. 
   Face plate  3100  also provides a distress button, pull ring, or other actuating device  3140  and apertures  3150  for a cell phone speaker and microphone to notify transportation or public safety officials of an emergency. In this embodiment, the transportation node apparatus  300  optionally comprises portions of embodiments, or adaptations thereof, of the emergency notification systems and methods disclosed in U.S. patent application Ser. No. 60/419,889, entitled TRANSPORTATION NOTIFICATION, EMERGENCY RESPONSE, AND SURVEILLANCE SYSTEM, and filed by Alan L. Bartlett on Oct. 21, 2002, which is herein incorporated by reference. To discourage patrons from unnecessarily triggering the actuating device  3140 , adhesive labeling is affixed to the face plate  3100  describing the nature of the actuating device  3140 . 
     FIG. 33A  depicts an exploded perspective view of the face plate  3100  in relationship to interlocking frame members  110  and  120  of the display assembly  100 , an edge light assembly  137 , and an edge light assembly bracket  131 . The edge light assembly  137  preferably comprises a plurality of board-mounted, energy-efficient, durable, high-intensity solid state white LEDs  139 , but may of course comprise any other suitable form of light emitter, including incandescent bulbs, fluorescent bulbs, and the like. We have found that four LEDs is suitable for a three-to-four inch wide display panel  130 , and that six LEDs is more suitable for a five-to-six inch wide display panel  130 . An electrical connector  138  is provided to connect the LEDs  139  to a switch-controlled or electric-circuit-controlled power source. 
   The edge light assembly bracket  131  comprises three fins  132 ,  134 , and  136  forming two parallel slots  133  and  135 . Fins  132  and  134  are adapted to clip onto the back portion  810  of the frame member  110 , which fits into slot  133 . Slot  135  is adapted to bracket both the light assembly  137  and the display panel  130  (and any accompanying display graphics and display panel backing). 
     FIG. 34  depicts a flow chart of one embodiment of an emergency response system and method  3400  for use with the present invention. In step  3410 , a transportation node patron activates a distress signal via the actuating device  3140 . In step  3420 , a prerecorded message is played at the transportation node telling the patron that an emergency call is being placed. After the prerecorded message has been played, in step  3450 , an alarm sounds. Meanwhile, in step  3430 , camera  320  captures one or more digital images, circuit board  360  processes the images, and antenna  330  transmits the images to transit or public safety officials. Also meanwhile, in step  3440 , a phone or distress signal receiver at the transit or public safety agency rings or signals that a distress call has been placed at the transit node. In step  3460 , the transit or public safety agency accepts the distress call, and in step  3470  a two-way voice connection is established between the agency and the transportation node, preferably via a cell phone apparatus housed inside or adjacent to the information display apparatus  100 . 
   Once the two-way voice connection has been established, in step  3480  the alarm at the transportation node is terminated to facilitate communications between transit or public safety officials and the patron. The patron is able to communicate the problem and the transit or public safety authority may respond appropriately. Alternatively, if an attack is in progress, the transit or public safety official can both see the transmitted images and hear the sounds transmitted by the cell phone apparatus. 
     FIG. 35  is a schematic diagram of one embodiment of a transportation node apparatus providing a backlit information display, overhead illumination, security camera, and cell phone communications. A main battery  3505 , solar panel  3510 , downlight LEDs  3515 , and a first circuit board module  3520  are housed in the overhead assembly  3595 . The first circuit board module  3520  comprises charge control circuitry  3522  to limit discharge of battery  3505  and to prevent overcharging by solar panel  3510 . The first circuit board module  3520  also comprises programmable light control circuitry  3524  to control the timing and duration of overhead illumination and display illumination. For example, light control circuitry  3524  is preferably programmed to prevent downlight LEDs  3515  and backlight LEDs  3580  from operating during daylight hours, or, alternatively, when the light control circuitry  3524  detects adequate ambient illumination based on charge received from solar panels  3510 . The first circuit board module  3520  is operatively coupled to a backlight button  3555 , a downlight button  3560 , and backlight LEDs  3580 , which are housed in the display assembly  3590 . 
   A second circuit board module  3525 , a standby battery  3540 , a camera module  3545 , a microphone  3535 , and an antenna  3530  are also mounted on or housed inside the overhead assembly  3595 . The second circuit board module  3525  has cell phone control circuitry  3526  to operate the cell phone microphone  3535  and speaker  3575 . The second circuit board module  3525  also has image processing circuitry  3528  communicatively coupled with a camera module  3545 . The image processing circuitry  3528  is preferably operable to store up to 15 minutes or more of video images so that investigators can view scenes leading up to a distress call. In a preferred embodiment, the image processing circuitry  3528  can also be activated remotely—not just by a distress signal—to capture and transmit images. 
   The second circuit board module  3525  is operatively coupled to wait button  3565  and emergency distress actuator  3565 , which are housed in the display assembly  3590 . A rechargeable standby battery  3540  is preferably provided in operative communication with the second circuit board module  3525 , so that transit authorities are automatically notified of main battery  3505  failure, and so that patrons can still place distress calls in the event of main battery  3505  failure. 
   Although the foregoing specific details describe various embodiments of the invention, persons reasonably skilled in the art will recognize that various changes may be made in the details of the apparatus of this invention without departing from the spirit and scope of the invention as defined in the appended claims. Therefore, it should be understood that, unless otherwise specified, this invention is not to be limited to the specific details shown and described herein.