Abstract:
An in-line sound module for a modular stack light system provides electrical and mechanical connectors to allow it to be placed anywhere in the stack. Axial orientation of the audio transducer and a flexible jumpering system allow preservation of central connectors between modules. In-line configuration permits multiple sound modules to be used in a stack light and to be teamed with different beacon modules. In one embodiment the in-line sound module may also include lamps to provide beacon functionality.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of and claims priority to U.S. application Ser. No. 15/082,247, tiled Mar. 28, 2016, which, in turn, is a continuation of U.S. application Ser. No. 14/153,568, filed Jan. 13, 2014, which has now issued as U.S. Pat. No. 9,307,309, and the entire contents of each of the afore-mentioned applications are incorporated herein by reference. 
     
    
     BACKGROUND INFORMATION 
       [0002]    The present invention relates to “stack-lights”, a structure used to convey operating and warning information in industrial environments, and in particular to a stack light that provides for a sound module that can be placed between beacon modules in the stack. 
         [0003]    Stack lights provide a short tower of different colored beacons that may be attached to, or in the proximity to, industrial equipment to provide a visual indication of equipment operating status to workers in the area. The tower promotes the visibility of the beacon lamps at different angles and locations while the different colors of the lamps as well as possible different flashing modes of lamps permit reliable communication of multiple types of information in a possibly noisy environment. In a typical installation, a simple stack light might have a red light indicating a machine failure or emergency, a yellow light indicating warnings such as over-temperature or over-pressure, and a green light confirming correct machine operation. Other combinations and colors are also possible. 
         [0004]    Stack lights are typically constructed in a modular fashion, with multiple beacon modules “stacked”, the first one on a base unit and then each on top of the next. This modular construction allows the number, color, and order of the beacons to be flexibly selected by customer. Each beacon module includes a lamp (for example an incandescent or LED assembly) held within a transparent housing, for example a cylindrical colored tube, through which the lamp may be viewed. Upper and lower electrical connectors allow interconnection of the beacons to each other or a base to form the tower. Each beacon module also includes an internal electrical conductor system that communicates electrical signals from the bottom of the module to its top so that when the modules are assembled together, electrical continuity is established along the height of the tower between the base and the various modules without the need for separate wiring operations. 
         [0005]    Typically each base provides a wire terminal block that may receive electrical wiring from an external switch source that controls the lighting of the beacons. Often that external switch source is an input/output (I/O) module associated with a programmable industrial control unit. Important status information developed during the execution of a control program on the industrial control unit may be relayed to the slack light for display. 
         [0006]    In this regard, the stack light normally receives a power “common” together with multiple “signal lines” each which controls the power to a given beacon. The internal electrical connector system of the beacon modules communicates each signal line from the given beacon module to the next beacon module in a manner that shifts the signal wires so to connect a different signal wire to the lamps of each module depending solely on the order of the module in the stack. 
         [0007]    It may be desired to add an audio alarm to the beacon modules of the stack light so as to consolidate warning systems in one location. For this purpose, a sound module may be constructed to be placed in the topmost position of the stack to receive electrical signal in the same manner as a beacon module but to energize an audio transducer rather than a lamp. 
       BRIEF DESCRIPTION 
       [0008]    The present invention provides a sound module that may be placed in-line between, for example, two beacon modules of a stack light. By permitting such in-line placement, multiple sound modules may be readily placed in a single stack light, and visually desirable upper locations in the light stack may be reserved for beacon modules. In one embodiment, a combined beacon and sound module is provided that may be flexibly placed anywhere in the stack. Providing a combined sound module and beacon module not only conserves tower height but also permits synchronized audio and light messages particularly useful for recorded spoken voices associated with given displays. 
         [0009]    Specifically then, in one embodiment, the invention provides an in-line sound module for use in a stack light of the type providing a set of beacon modules interlocking to each other and to a base unit by means of interlocking mechanical connectors and interfitting electrical connectors positioned at a top and bottom of each beacon module and at a top of the base unit, the mechanical connectors and electrical connectors together allowing multiple beacon modules and one base to be mechanically assembled into a tower with electrical communication between the base and each beacon module. The in-line sound module includes a housing having sidewalls defining a chamber between an upper and lower face. First and second mechanical connectors are positioned, respectively, at the upper and lower face and adapted to releasably interlock with corresponding mechanical connectors of the beacon modules or a base, and first and second electrical connectors are positioned, respectively, at the upper and lower face and adapted to releasably interface with corresponding electrical connectors of beacon modules or a base. An audio transducer is held within the chamber lo direct sound into the chamber and through openings in the sidewall and electrical conductors extending between the first and second electrical connectors and from the second electrical connector to the audio transducer. 
         [0010]    It is thus a feature of at least one embodiment of the invention to provide a sound module that does not need to claim the top position of the tower bus providing improved aesthetics, flexibility, and the ability to use multiple sound modules in a given stack light. 
         [0011]    The audio transducer may provide for electrically induced movement along an axis generally centered within the housing extending between the upper and lower faces. 
         [0012]    It is thus a feature of at least one embodiment of the invention to permit an orientation of the audio transmitter well adapted for “Omni” radiation patterns and minimizing module height and visual obstruction by the audio transducer. 
         [0013]    The active surface of the audio transducer may have an area of at least 50% of a cross-sectional area of the chamber perpendicular to the axis. 
         [0014]    It is thus a feature of at least one embodiment of the invention to maximize the area of the audio transducer for increased sound output and low range frequency response. 
         [0015]    The first and second electrical connectors may be substantially centered within the upper and lower face and the conductors between the first and second electrical connectors are flexible to route around an edge of the audio transducer. 
         [0016]    It is thus a feature of at least one embodiment of the invention to permit use of the sound module with beacons having center connector arrangements. 
         [0017]    The conductors between the first and second electrical connectors may be side-by-side parallel conductive elements supported in a common flexible matrix. 
         [0018]    It is thus a feature of at least one embodiment of the invention to provide a conductor routing system that permits large transducer areas. 
         [0019]    The in-line sound module may further include a sound directing structure within the chamber directing axial sound waves from the audio transducer through a sidewall. 
         [0020]    It is thus a feature of at least one embodiment of the invention to provide flexibility in the orientation of the transducer independent of the necessary propagation directions of the sound through the use of a sound director. 
         [0021]    The sound directing structure provides a horn element. 
         [0022]    It is thus a feature of at least one embodiment of the invention to provide improved acoustic impedance matching between the audio transducer and the surrounding air in a compact in-line module. 
         [0023]    The sound directing structure may be movable to change a direction of the directing of axial sound waves from the audio transducer through a sidewall. 
         [0024]    It is thus a feature of at least one embodiment of the invention to permit focusing of the sound in particular directions as may be required in a factory environment. 
         [0025]    The in-line sound module may further include at least one lamp within the housing and wherein electrical conductors extend between at least one lamp and the second connector. 
         [0026]    It is thus a feature of at least one embodiment of the invention to permit combining beacon modules and sound modules, for example, for improved synchronization between sound and beacon activity. 
         [0027]    The audio transducer may form one wall of the chamber. 
         [0028]    It is thus a feature of at least one embodiment of the invention to provide improved coupling of the audio transducer to air within the chamber. 
         [0029]    The invention may provide a plastic dome cover having a lower face having a second mechanical connector adapted to releasably interlock with corresponding mechanical connectors of the beacon modules or the base. 
         [0030]    It is thus a feature of at least one embodiment of the invention to permit alternative top treatments for the stack when the sound module need not be placed at the top of the stack. 
         [0031]    The plastic dome cover may be transparent and further includes at least one lamp and an electrical conductor positioned on the lower face and adapted to releasably interface with corresponding electrical connectors of the beacon modules or the base. 
         [0032]    It is thus a feature of at least one embodiment of the invention to permit the prominent top of the stack to be used for a beacon module. 
         [0033]    These particular features and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a perspective view of a stack light assembled on a base with several beacon modules, in-line sound modules, and a dome and showing elevational cross-sections of one beacon module with one audio in-line module having an internal chamber supporting an audio transducer; 
           [0035]      FIG. 2  is an elevational cross-section of the in-line sound module of  FIG. 1  taken in a perpendicular plane of the cross-section of  FIG. 1  showing the routing of the electrical connections around the audio transducer with a flexible conductor; 
           [0036]      FIG. 3  is an exploded perspective view of an external rotatable sound direction sleeve that may fit over the in-line sound module; 
           [0037]      FIG. 4  is a side-by-side plan cross-section and fragmentary elevational cross-section of the chamber of  FIG. 1  holding an internal rotatable sound director; 
           [0038]      FIG. 5  is an elevational cross-section of a dome module for fitting on top of the stack light; 
           [0039]      FIG. 6  is an elevational cross-section of an alternative embodiment of the in-line sound module showing alternative transducer locations and a circuit card for synthesis of different audio tones; and 
           [0040]      FIG. 7  is a block diagram of an audio synthesis circuit for use with  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    Referring now to  FIG. 1 a    stack light  10  constructed according to the present invention may be assembled of multiple interlocking beacon modules  12   a  and  12   b  and multiple in-line sound modules  14   a  and  14   b , a dome  18  and a base module  16 . 
         [0042]    In one embodiment, the lowest most base module  16  may provide a lower flange  19  having one or more openings  20  for receiving machine screws  22  or the like to fasten the flange  19  and hence the base module  16  to a surface  24  of a machine or the like. 
         [0043]    The upper surface of the base module  16  (shown as a figure inset) may expose a centered electrical connector  26   a  that may attach to a corresponding electrical connector  26   b  on the lower surfaces of the lowest beacon module  12   b.    
         [0044]    Generally, a connector similar to electrical connector  26   b  will also be on the lower surface of the other beacon module  12   a  and the in-line sound modules  14   a  and  14   b  and dome  18  (in some embodiments). Further, electrical connectors  26  similar to electrical connector  26   a  will also exist on the upper surface of each of the beacon modules  12  and in-line sound modules  14 . In this way, inter-engagement of electrical connectors  26  in the assembled stack light  10  may provide electrical communication between each of the base module,  16  beacon modules  12 , in-line sound modules  14  and dome  18  as will be described. 
         [0045]    The upper end of the base module  16  also provides a portion of a mechanical interlocking system used to hold the modules together in a tower. This portion of the mechanical interlocking system is in the form of radially extending tabs  28 . Similar radially extending tabs  28  exist at the upper end of each of the beacon modules  12  and the in-line sound modules  14 . 
         [0046]    The radially extending tabs  28  may be received by a second portion of the mechanical interlocking system in the form of twist type bayonet rings  30  rotatably affixed to the lower ends of each of the beacon modules  12 , in-line sound modules  14 , and dome  18 . Such bayonet rings  30 , as generally understood in the art, provide ledges on their inner diameter that may capture the radially extending tabs  28  against a helical ledge in the manner of inter-engaging threads while providing a slight pocket at the end of rotation forming a detent that locks the tabs  28  and bayonet rings  30  into predetermined compression. 
         [0047]    Inter-engagement tabs  28  and bayonet rings  30  allow the base module  16 , the beacon modules  12 , the in-line sound module  14 , and the dome  18  to be assembled into the stack light  10 . This assembly creates a tower extending generally upward from the base module  16  through one or more beacon modules  12  and one or more in-line sound modules  14  each of which may be independently controlled to display a predetermined color of illumination or audio signal depending on the module type. An O-ring seal  38  may be provided at the junction between adjacent attached beacon modules  12 , in-line sound modules  14 , base module  16 , and dome  18  to reduce the ingress of environmental contamination when the modules are connected. 
         [0048]    Referring still to  FIG. 1 , each of the beacon modules  12  and in-line sound modules  14  may provide a housing  32 , for example, constructed of electrically insulating thermoplastic. In the following example, where the in-line sound module  14  also provides for beacon functionality, the housings  32  of both of the beacon modules  12  and in-line sound modules  14  will be of transparent (possibly tinted) thermoplastic to allow the passage of light, it will be understood that when an in-line sound module  14  does not include a lamp, an opaque thermoplastic material may be employed. 
         [0049]    The housings  32  may generally present a cylindrical periphery in diameter consistent among the modules. Standard diameters for stack lights  10  include 30 mm, 40 mm, 50 mm, 60 mm, 70 mm and 100 mm. 
         [0050]    The depicted lowermost beacon module  12   b  may receive from the base module  16  a common voltage along common conductor  34  and multiple signal conductors  35 . The conductors may be received through lowermost connector  26   b  when joined with connector  26   a.  In this regard, electrical connectors  26   a  and  26   b,  for example, may be male and female versions of the same connector to be mechanically inter-engageable or may be identical connectors reoriented as in the case of hermaphrodite connector systems. 
         [0051]    For simplicity, the electrical connectors  26   a  and  26   b  (and all connectors  26  in  FIG. 2 ) are depicted with only four conductive inserts  41  (for example, conductive pins or sockets) which may each receive the common conductor  34  and three signal conductors  35   a - 35   c.  As is understood in the art, each conductive insert  41  provides an electrically independent conductive path within mating electrical connectors  26 . 
         [0052]    Referring still to  FIG. 1 , the connector  26   b  in beacon module  12   b  may be attached to and communicate with, for example, a printed circuit board  40  carrying on it multiple light emitting diodes (LEDs)  42 . As shown, LEDs  42  are connected between the common conductor  34  and signal conductor  35   a  attached to inserts  41  occupying the extreme left and right positions of the connector  26   b.  Accordingly, electrical power applied to signal conductor  35   a  will energize the LEDs  42  of beacon module  12   b  so that the light may be viewed through transparent housing  63 . 
         [0053]    Although the LEDs  42  are shown connected in parallel, series connections are also possible using constant current driving circuitry. Current sharing resistances for each LED  42  when connected in parallel have been omitted for clarity. 
         [0054]    The upper edge of the circuit board  40 , in turn, may attach to a connector  26   c  being, as noted, identical to connector  26   a . Circuit traces on a printed circuit board  40  provide common conductor  34  and join identical locations of connectors  26   b  and  26   c  (in the leftmost position as shown in  FIG. 1 ). Signal conductor  35   a  used to control the LEDs  42  of beacon module  12   a  do not pass to connector  26   c,  however, and signal conductors  35   b  and  35   c  are attached to connector  26   c  after being shifted one connector position to the right so that signal conductor  35   b  is now at the rightmost conductive insert  41  of connector  26   c.    
         [0055]    It will be understood that each of the beacon modules  12  and in-line sound modules  14  will have generally the same interconnections between their lower and upper connectors  26 . In this way, as signals move upward through the beacon modules  12  or in-line sound modules  14 , the identity of the rightmost signal line in the receiving lower connector  26  will be a function of the order of the given module in the stack of the tower. This automatically provides independent electrical conductors from the base module  16  to each given beacon module  12  or in-line sound module  14  according to module stack order without the need for adjustment of the internal wiring of the beacon modules  12  and in-line sound modules  14  or the setting of internal addresses or the like. The number of conductive inserts  41  in the connector  26  and signal conductors  35  determine the limit of the number of beacon modules  12  and in-line sound modules  14  that may be stacked in this manner. 
         [0056]    Referring still to  FIG. 1 , the depicted lowermost in-line sound module  14   b  will have a connector  26   d  engaging with connector  26   c  of lowermost beacon module  12   b  when the two are attached. This connector  26   d  may likewise be attached to a first printed circuit board  50   a  contained within the housing  32  of the in-line sound module  14 , but unlike printed circuit board  40  of beacon module  12   b , circuit board  50   a  extends only part way up the inside of the housing  32  stopping just below an audio transducer  52  forming a lower wall of an audio chamber  54  in the housing  32 . This lower wall extends generally perpendicularly to an axis  56  of the housing  32  generally aligned with an axis of symmetry of the cylinder of the housing  32  and extending between the lower connector  26  and an upper connector  26   c  of the housing  32 . 
         [0057]    The circuit board  50   a  may include a subset of the LEDs  42  of the in-line sound module  14   b  attached in the same manner as in beacon module  12   b . All of the traces of the printed circuit board  50   a  terminate at solder pads  62  at its upper edge as will be discussed below. 
         [0058]    The audio transducer  52  may be a brass plate having an adhered piezoelectric material, or maybe a dynamic audio transducer employing coil and magnet technology as is generally understood in the art. The audio transducer  52  is generally supported at its edges near the inner walls of the housing  32  so that flexure of an active surface of the audio transducer  52  generates acoustic pressure waves traveling upward along axis  56 . The edges of the audio transducer  52  may be substantially sealed to the housing  32  to prevent acoustic leakage therethrough. 
         [0059]    An upper wall of the audio chamber  54  may be provided by a transparent thermoplastic wall  58  providing a shape that forms an acoustic horn guiding acoustic energy from the transducer  52  out of openings  60  distributed around the side wall of the housing  32 . As is understood in the art, an acoustic horn is a shape dial provides an improved acoustic impedance match between a sound source and free air. 
         [0060]    A center section of the thermoplastic wall  58  is depressed in the horn shape to receive a second printed circuit board  50   b.  Referring also to  FIG. 2 , solder pads  64  at a lower edge of the printed circuit board  50   b  may communicate with solder pads  62  of printed circuit board  50   a  by means of a juniper  66 , being, for example, a flexible printed circuit board having parallel conductors  68  held in a flexible insulator  70  or a section of ribbon cable or the like. The jumper  66  allows continuity to be established between circuit boards  50   a  and  50   b  despite the interposition of the acoustic transducer  52  by diverting conductors around an edge of the acoustic transducer  52  and wall  58  through small openings for this purpose. The upper edge of circuit board  50   b  attaches to a connector  26   e  in the same manner as described with respect to beacon module  12   b.    
         [0061]    Circuit board  50   b  holds a remaining subset of the LEDs  42 , wired as with the previous subset on circuit board  50   a  between the common conductor  34  and the leftmost conductor (in this case, signal conductor  35   b ). The same shifting right of the traces of the printed circuit board  50   b  is performed before receipt of those conductors by connector  26   e  attached at the upper edge of circuit board  50   b.    
         [0062]    Referring now to  FIG. 3 , a rotatable sleeve  71  may be fit around the outer cylindrical periphery of the housing  32  of either or both of the in-line sound modules  14  to cover some openings  60  and to expose other opening  60  within a limited angular range aligned with a window  72  in the sleeve  71 . In this way, sleeve  71  may be used to direct sound preferentially in a limited range of corrections by rotation of the sleeve  71 . 
         [0063]    Referring now to  FIG. 4 , alternatively, a focusing director  74  may be placed inside of the housing  32  between the lower wall of the chamber  54  formed by acoustic transducer  52  and the upper wall  58  of the chamber. This focusing director blocks the exit of sound through a range of the opening  60  to provide a similar focusing of sound in one direction as provided by sleeve  71 . Director  74  may be manipulated by means of a knob  76  protruding through a slot passing partially around the outer wall of the housing  32 . 
         [0064]    Referring now to  FIG. 5 , the construction of an in-line sound module  14  allows the uppermost position of the tower to be occupied, for example, by a simple plastic dome  80  constructed of a transparent thermoplastic material and having a lower bayonet ring  30  to attach to an uppermost beacon module  12  or in-line sound module  14 . This dome  80  provides a low profile finished look to the tower that protects any upper connector  26  of the penultimate module. In one embodiment, the dome  80  may also include a circuit board  82  having LEDs  42  to provided beacon functionality. The circuit board  82  is connected at its lower edge to a connector  26   f  so as to permit the dome  80  to receive the necessary signal conductor  35 . 
         [0065]    Referring now to  FIG. 6 , it will be appreciated that the in-line sound modules  14  need not include lamp assemblies of LEDs  42  and thus may provide for an opaque housing  32 ′. In one embodiment, both a lower wall of the chamber  54  and upper wall of the chamber  54  may be formed of separate acoustic elements  52   a  and  52   b,  for example, to provide for greater sound output. Either one of the circuit boards  50   a  or  50   b  may include a sound modulation module  86  allowing a variety of different sounds to be generated beyond a simple steady tone, for example intermittent tones having different frequencies, tones that rise and fall in frequency, and the like. 
         [0066]    Referring to  FIG. 7 , electrical power from the signal conductor  35  activating the in-line sound module  14  may be provided to a sound function generator  90  communicating with the audio transducer  52  and with a switch  92  and one or more control potentiometers  94  allowing selection of the particular audio tone and its parameters, for example volume, upper tone frequency, lower tone frequency, and modulation speed. 
         [0067]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second”and other such numerical terms referring to Structures do not imply a sequence or order unless clearly indicated by the context. 
         [0068]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including”and “having” are intended to be inclusive and mean that there may be additional elements or features other titan those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood dial additional or alternative steps may be employed. 
         [0069]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties. 
         [0070]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments, including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.