Abstract:
A device for presenting multiple illuminated messages and a method for making same. The device includes a uniformly thick panel of transparent material having at least one elongated and continuous passageway therein forming a message to be indicated. The passageway is filled with gas and materials that emit light.

Description:
This application claims benefit of Provisional application 60/070,461, filed Jan. 5, 1988. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a sign that is capable of presenting two separate illuminated messages or signals in substantially the same or side-by-side surface area, one message or signal being illuminated while the other remains on or is extinguished. In addition, the invention also contains provision for novel means of supplying heat to the sign, enabling it to be operated in cold climates. 
     SUMMARY OF THE INVENTION 
     The invention is applicable to any situation in which two or more different messages are to be conveyed. For example, this may include many applications within the traffic and pedestrian control areas, &#34;OPEN/CLOSED&#34; signs, &#34;VACANCY/NO VACANCY&#34;, etc. 
     The sign consists of a uniformly thick panel of transparent material (for example glass) in which separate first and second elongated and continuous passageways are presented, each forming the message to be indicated. The passageways are filled with gases and materials that emit light when an electrical discharge is passed through them via electrodes placed at each end of the channels. The first channel (viewed from the front of the sign) utilizes a gas (or gases) only, so that when it is not energized it is transparent, giving full view of the (energized) second channel. Such a gas is neon. The second channel may either contain a gas or gases, or an argon-mercury mixture. If such a mixture is used then at least part of the transparent material comprising the walls of this channel is coated with a phosphor that emits light of a chosen color under excitation by radiation emitted from the argon-mercury discharge. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a front view of a panel or plate having a pedestrian sign formed thereon; 
     FIG. 2 is an exploded isometric view of a panel embodying the invention; 
     FIG. 3 is a sectional view through the panel of FIG. 1 and embodying the invention; 
     FIG. 4 is a sectional view through an alternate construction of the panel embodying the invention; 
     FIG. 5 illustrates a prior art pedestrian sign; 
     FIG. 6 illustrates a prior art discharge tube in a pedestrian sign environment; 
     FIG. 7A is a sectional view through a further alternate construction of the panel; 
     FIG. 7B is a sectional view through a still further alternate construction of the panel; 
     FIG. 8 is a front view of a mask; 
     FIG. 9A is an isometric view of a pedestrian sign embodying the invention; 
     FIG. 9B is a sectional view through a housing for the pedestrian sign shown in FIG. 9A; 
     FIG. 10 is a front view of a panel embodying the invention for indicating a left or a right pointing arrow; and 
     FIG. 11 is a front view of a panel embodying the invention for lane use control by indicating an &#34;X&#34; or a down pointing arrow. 
    
    
     DETAILED DESCRIPTION 
     To illustrate the advantages and mode of construction and operation, in this brief description we concentrate on traffic control products in general, and on the symbols (orange hand and white walking man) that internationally represent &#34;WALK/DONT WALK&#34;. (Other applications in the traffic control field include, but are not restricted to, pedestrian control via the words &#34;WALK/DONT WALK&#34;, lane use, lane control via an &#34;X&#34; and a down pointing arrow {FIG. 11}, direction indicators via left and right pointing arrows {FIG. 10}.) FIG. 1 shows the front view (i.e. the direction from which it is to be viewed) of the pedestrian crossing signal. The front (first) passageway or channel is in the form of a hand (&#34;DONT WALK&#34;) and contains neon gas. The second channel (behind and separate from the first) is in the form of a walking man (&#34;WALK&#34;) and contains argon gas and mercury. The area that comprises the back of the second channel is coated with a phosphor that emits white light when the channel is energized. Thus, when it is desired to convey the &#34;DONT WALK&#34; message, the neon (front) channel is energized, and when it is desired to display the &#34;WALK&#34; message, the argon/mercury/phosphor (back) channel is energized. Since the &#34;DONT WALK&#34; message is transparent when not energized, the &#34;WALK&#34; message is clearly seen when it is energized. Each channel is terminated with electrodes that provide the electrical energy required for energization, and electrical lead-in wires (1 &amp; 2), that exit through the rear of the plate, contact these electrodes. Holes (3 &amp; 4) are provided which provide the access necessary to remove air and fill the channels with the necessary gases. 
     When packaged as a pedestrian control signal, such a device also offers the following advantages over prior art: 
     Reduction of at least 50% in size of signal head without any reduction in size of individual message presented. 
     Reduced energy consumption 
     Reduced maintenance 
     Mode of Construction 
     FIG. 2 shows an exploded view of one possible mode of construction of the pedestrian crossing signal. It consists of five transparent plates (5,6,7,8,9). Plates 6 and 8 have cut through them channels in the patterns of a walking man and a hand respectively. The back plate (5) has a phosphor applied to its inner surface in the pattern of a walking man in such a place that when it is interfaced with plate 6 the pattern coincides with that of the &#34;man&#34; channel in plate 6. Plate 7 comprises both the front plate of the WALK sign and the back plate of the DONT WALK sign. Both plates 5 &amp; 7 have access holes cut through them for the introduction of electrical lead in wires connected to the electrodes (1 &amp; 2) and fill tubes (3 &amp; 4). Plate 9 is a transparent plate only, serving as a front plate for the DONT WALK sign. 
     The plates are assembled and electrodes and lead-in wires are added. The layers are sealed so that one whole unit is obtained and the appropriate gases and mercury introduced via fill tubes, which are then hermetically closed. The sealing may be achieved in a variety of ways, including heat (fusing), glass frit, or suitable adhesives. FIG. 3 represents a section through the sealed unit. The structure shown in broken lines will be explained below in relation to FIGS. 7A and 7B. 
     A section through a completed unit, which is the result of a second possible mode of construction, is shown in FIG. 4. Here, plates 6, 7 &amp; 8 in the previous example are replaced by a single plate (10). In the front side of this plate is formed, via pressing, molding, routing or other means a trough 30 or channel in the form of the hand symbol. Similarly, the walking man symbol is formed by a trough 31 in the backside of the plate. Assembly is then achieved as in the previous example. 
     Heat Management for Operation in Cold Climates 
     The prior art in the discussed areas of application includes the use of messages presented via light generated by discharge tubes. For example, FIG. 5 shows a pedestrian crossing signal that presents the symbols in a side-by-side manner. FIG. 6 shows a neon discharge tube (11) used to back light a transparent surface in the form of a hand, and a argon/mercury/phosphor tube 12 is used to back light a transparent surface in the form of a walking man. The successful operation of the argon/mercury/phosphor tube depends upon the maintenance of mercury vapor pressure within the tube, and as the ambient temperature drops, the amount of light emitted from the tube drops. Hence a noticeable decrease in brightness can occur, even at temperatures as high as 10° C. Obviously, this is undesirable in many situations. It is therefore advantageous to maintain the temperature of the argon/mercury/phosphor light emitter at the optimum for maximum tube brightness. This occurs at around 35° C. The current invention allows opportunities to achieve this. As shown in FIGS. 7A and 7B, and in broken lines in FIGS. 3, heat may be applied in the form of electrical energy by the placement of an electrical heater 32 on the rear of plate 5. Because the rear of plate 5 consists of a flat surface it allows an electrical heater wire 33 and thermostat 34 in series to be applied to it. The heater may consist of an electrical wire or printed &#34;thick film&#34; heating element well known in the art, which extends co-extensively with the applied phosphor 35 pattern. In this manner it is possible to control the supply of electrical energy to the heater wire to periods of time when the temperature of the rear of plate 5 is below a specified setting on the thermostat. Application of a heater in this way does not interfere with the production or transmission of light. Furthermore it allows for an efficient transfer of heat to the required area. FIGS. 7A, 7B and the broken lines of FIG. 3 show a representation of a heater wire and thermostat applied to the &#34;molded&#34; and &#34;cut&#34; version of the pedestrian crossing sign. A supporting medium 36, such as an adhesively backed tape or foil sheet, is utilized to hold the wire or tape 33 and thermostat in place on the rear side of the rear plate 5. 
     Additionally, the temperature of the argon/mercury/phosphor sign is constantly elevated above that of ambient by the warming action of the neon sign behind which it sits and in which it is in direct contact. 
     FIG. 7B illustrates a side-by-side sign 40 wherein a left side 41 of the sign viewed in the direction 42 has a neon discharge channel 43 and the right side 44 has a argon/mercury/phosphor channel 45 separate from the channel 43. Thus, the wire or thin film heater wire 33 is only required to be in association with the pattern formed by the channel 45 having the phosphor liner 35. In this embodiment, the message indica can be simultaneously or alternatingly displayed. 
     Mounting of Signal Panel to Produce Pedestrian Crossing Signal Unit 
     A mask 13 (FIG. 8) is attached to the front surface of the plural plates or panel 48 so that only those parts of the symbols that are intended to be visible are seen. The panel is then mounted in a housing 50 (FIG. 9A) having an open front side 51 and a closed backside 52 (see FIG. 9B). This may take form of housing well known in the art or an adaptation thereof. The housing 50 includes a removable cover or hinged door 53 into which the panel is mounted in such a manner that the messages are visible. A visor 54 may be added in the customary way, or alternatively a micro-louvered coating (such as manufactured by the 3M Company) may be applied to or near the panel&#39;s front surface. Such a coating or film offers the advantage of allowing light to pass only at a defined angle, thus eliminating the well known phenomenon of &#34;washout&#34; of the signal under periods of direct illumination from the sun. It may also allow the signal to be clearly visible in full sunlight without the aid of a visor or other form of shade. The assembly may also include a transparent plate 55 mounted a short distance in front of the front surface of the panel 48. This serves both as a protective device and as a further means of minimizing heat loss in cold weather. A device (power supply 56) for supplying the necessary voltage and current to illuminate the messages is provided inside the housing 50. Appropriate seals and gaskets 57, 58 and 59 are employed to keep the weather out of the housing 50. A main electrical supply wire 61 is connected to the power supply 56 and extends through a hole in a wall of the housing 50. 
     Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.