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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/121,897, filed on Feb. 27, 1015, the entire disclosure of which is hereby incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     This disclosure generally pertains to improved workplace safety, and more particularly, to a hazard alert device that alerts an individual of a potential hazard when a gate of a barrier located at the perimeter of an elevated surface is open and/or unlocked. 
     BACKGROUND 
     Many industrial and commercial facilities have elevated floor surfaces with perimeter railings and operable gates which allow for the movement of supplies, equipment, and other materials on and off of the elevated floor. In some situations, the perimeter will have solid walls and gates. There are serious safety concerns whenever these gates need to be opened, with the gate never being opened longer than absolutely necessary. However, for convenience and other reasons, there may be incidences where the gate is left open for extended periods of time. 
     Conventional gates lack a method and system to alert people of hazards associated with an open floor edge. Further, such conventional gates lack a method of reminding people to promptly close gates of safety barriers. 
     SUMMARY 
     In an embodiment of the invention, a hazard alert device includes a barrier sensor and a signaling device including a delay mechanism. In an embodiment, an elevated surface has a barrier and a gate disposed along an edge of the elevated surface, with the gate being switchable between a closed position that obstructs the edge of the elevated surface and prevents movement of people and/or material, and an open position that allows for the movement of people and/or material. The barrier sensor is configured to sense whether the gate is in the closed position and to generate a closed signal in response thereto. The signaling device is in operative communication with the barrier sensor, and is configured to provide a visible alarm and/or an audible alarm when the barrier sensor has not generated the closed signal. The delay mechanism, once activated, is configured to silence the audible alarm for a predetermined period of time, to maintain the visible alarm throughout the period of time, and to reinitiate the audible alarm once the predetermined period of time has elapsed. 
     The hazard alert device utilizes a sensor, or multiple sensors, to detect when a fall-hazard exists. A fall-hazard may exist whenever the elevated movable barrier is not in the fully closed position. In some embodiments, the barrier sensor may be equipped with a coded magnet that signals that the gate is in the fully-closed position. In some embodiments, the barrier sensor detects that the gate is both in a fully-closed position and/or locked position. 
     In some embodiments, such as for use on a loading dock, the fall-hazard does not exist unless both the safety barrier is opened and a truck is not present; so the sensors may be arranged to detect both “no truck is present” and “the gate is not fully closed.” 
     According to an embodiment, the hazard alert device may include both audible and visual signals that provide both a continuous alert as long as the elevated movable barrier is in the opened position. Upon detecting the fall-hazard, the device activates the visual and audible signals. In some embodiments, this alert may include flashing lights and a high-pitched pulsing horn. There may be multiple volume settings to ensure that the horn is loud enough to draw attention to the hazard situation. 
     When the gate of the barrier needs to be opened for the movement of material, or other items, the hazard alert device may provide a mechanism to silence the horn while the open gate is actively in use. According to various embodiments, the device may have a “snooze” button that, once pressed, silences the horn for an appropriate period of time. A flashing light, or other visual warning, may continue to signal the hazard condition during this time. In the event that the gate is left opened too long, and the “snooze period” had elapsed, the audible signal may resume. 
     In another embodiment, a method is provided for securing an elevated surface. According to an embodiment, an elevated surface may include a barrier along an edge of the elevated surface. The barrier may include an opening therethrough that is configured to allow the movement of people and/or materials with a gate residing within the opening, with the gate being movable between a closed position and an open position. The method includes sensing when the gate is in the open position, and in response to sensing the gate is in the open position, activating an audible alarm and a visible alarm, and enabling the audible alarm to be selectively deactivated for a period of time. 
     In a further embodiment, a method is provided for securing an elevated surface. According to an embodiment, the elevated surface may include a barrier along an edge of the elevated surface. The barrier may include an opening therethrough configured to allow the movement of people and/or materials with a gate residing within the opening. The method includes sensing when the gate is in the open position using a barrier sensor, sensing when a vehicle is not proximate the opening using a vehicle sensor, and in response to sensing the gate is in the open position and a vehicle is not proximate the opening, activating an alarm. 
     In another embodiment, a hazard alert system is provided for an elevated surface. The hazard alert system includes a barrier, a locking mechanism, and a hazard alert device. The barrier includes first and second swing gates pivoting about a pair of spaced vertical axes. The first and second swing gates are alignable along a plane. The locking mechanism locks the first and second swing gates in alignment along the plane such that the first and second swing gates are switchable between a locked position that locks the first and second swing gates together and prevents movement of people and/or material, and an unlocked position that allows for the movement of people and/or material. The hazard alert device includes a barrier sensor, a signaling device, and a controller located internal to the signaling device. The barrier sensor has a swing gate mounted portion and a locking mechanism mounted portion. The portions are in alignment when the first and second swing gates are aligned along the plane and when the locking mechanism is in locked position. The signaling device is mounted to the barrier located adjacent with and in alignment with one of the first and second swing gates. The controller is operatively connected to the swing gate mounted portion of the first sensor and also operatively connected to an audible alarm and a visible alarm. The controller is configured to silence the audible alarm for a predetermined period of time, maintain the visible alarm throughout the predetermined period of time, and reinitiate the audible alarm once the predetermined period of time has elapsed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, that are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the embodiments of the invention. 
         FIG. 1  is a perspective view of the hazard alert device for a swing gate, according to an exemplary embodiment of the invention. 
         FIG. 2  is a detailed view of the hazard alert device of  FIG. 1 , more clearly showing the signaling device and the barrier sensor, according to an exemplary embodiment. 
         FIG. 3  is a front view of the hazard alert device, with the signaling device and barrier sensor being disconnected from the gate, according to an exemplary embodiment. 
         FIG. 4  is a block diagram of the hazard alert device, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before various exemplary embodiments of the invention are discussed in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and can be adapted to suit many different types of gates, and can include components that can detect a fall-hazard in various ways. As used herein, a “gate” is intended to include various types of gates (such as a swing gate shown in  FIGS. 1 and 2 ), a slide gate, a tilt gate, a scissor gate), doors, and other known moveable access devices. 
       FIGS. 1 and 2  show an exemplary embodiment of the hazard alert device  15  including a barrier sensor  10 , a signaling device  1 , and a delay mechanism (such as snooze button  2 ) used to activate a “snooze” mode. Similarly,  FIG. 3  shows the hazard alert device  15  disconnected from the elevated floor-edge gate  11 . The hazard alert device  15  may be battery powered or connected to a power outlet. The hazard alert device  15  protects against the dangers associated with an elevated surface (such as platform  16 ) having a barrier  13  with an elevated floor-edge gate  11 . Examples of such elevated surfaces include, but are not limited to: balconies, work platforms, storage mezzanines, loading docks, surfaces above pits, and catwalks. 
       FIGS. 1 and 2  show the barrier  13  as including an opening extending between first and second vertical posts  18   a ,  18   b  of the barrier  13 . An elevated floor-edge gate  11 , including first and second elevated floor-edge gates  11   a ,  11   b , is provided within the opening along an edge  14  of the platform  16 . The elevated floor-edge gate  11  is movable between a closed position (shown) and an open position (not shown). The closed position obstructs the edge  14  of the platform  16  and generally prevents the movement of people and/or material from passing through the opening, while the open position allows for people and/or material to freely pass through the opening. 
     A locking mechanism (e.g., slide-latch  12 , discussed below) may be incorporated to couple the first and second elevated floor-edge gates,  11   a  and  11   b , and to prevent the first and second elevated floor-edge gates,  11   a  and  11   b , from unintentionally opening. Decoupling the locking mechanism causes the first and second elevated floor-edge gates,  11   a  and  11   b , to move from a locked position to an unlocked position.  FIG. 1  illustrates an example locking mechanism. In this example, the locking mechanism is a slide-latch  12  that moves laterally, in a direction generally parallel to the opening, to disconnect the first elevated floor-edge gate  11   a  from the second elevated floor-edge gate  11   b . The first elevated floor-edge gate  11   a  is hingedly connected to the first vertical post  18   a  using a first hinge (not shown), while the first elevated floor-edge gate  11   b  is hingedly connected to the second vertical post  18   b  using a second hinge (not shown). After the slide-latch  12  is decoupled, at least one of the first elevated floor-edge gate  11   a , or the second elevated floor-edge gate  11   b , pivots from the closed position to the open position. Upon moving the slide-latch  12  from the locked to unlocked position, the first sensing element (shown as forming part of magnet  7 ) is no longer aligned with the second sensing element (shown as forming part of receiver  17 ). 
     The barrier sensor  10 , mounted to the sensor bracket  6 , includes the magnet  7 , and the receiver  17 . The barrier sensor  10  is configured to transmit a signal (may include first and second return signals  113 ,  114  as shown in  FIG. 4 ) to determine whether the elevated floor-edge gate  11  is in the closed position. According to an embodiment, the barrier sensor  10 , shown in  FIGS. 1-3 , may be a dual-channel magnetic sensor, for example, a SMS03 Series Rectangular Safety Magnetic Sensor, commercially available from Carlo Gavazzi of Buffalo Grove, Ill. However, persons of ordinary skill in the art would appreciate that in other embodiments the barrier sensor  10  may comprise other types of sensors including, but not limited to: a magnetic switch, a electromechanical switch, a electromagnetic sensor, an ultrasonic proximity sensor, a proximity switch, a photoelectric eye, and/or a Hall Effect sensor. 
     As discussed below in reference to block diagram of  FIG. 4 , in further embodiments, the barrier sensor  10  may have redundant (dual-channel) electrical contacts that may be in an open position when the receiver  17  is not within a predetermined distance from the magnet  7 . When the electrical contacts are in an open position, the flow of electrical current through the first and second wires that are connected to the signaling device  1  is interrupted. As shown in  FIGS. 1-3 , according to an embodiment, the first and second wires may be housed in the same sensor wire casing  9 . However, in further embodiments, the first and second wires may be housed in different wire casings  9  to generate further redundancy. 
     According to an embodiment, signaling device  1 , mounted to module bracket  4 , may be in operative communication with the barrier sensor  10 , and may be configured to provide a visible alarm  117  (such a flashing light  3  shown in  FIGS. 1-3 ) and/or an audible alarm (such as pulsing horn  5  shown in  FIGS. 1-3 ) in response to the elevated floor-edge gate  11  not being in the closed position. According to an embodiment, the flashing light  3  and the pulsing horn  5  may be continuously active until the first and second elevated floor-edge gates,  11   a  and  11   b , are brought into the closed position or until the snooze mode  119  is initiated, as discussed in greater detail below. According to an embodiment, the visible alarm may comprise one or more light emitting diodes (“LEDs”) located on the front and back of the signaling device  1  that allow the visible alarm  117  to be seen at multiple angles (such as at elevated and ground levels). 
     The delay mechanism  120  (shown as snooze button  2  in  FIGS. 2 and 3 ) is shown as being formed within the signaling device  1 , however, this is not required. According to an embodiment, the delay mechanism  120  allows the pulsing horn  5  to be temporarily silenced by a user manually pressing a snooze button  2  when material handling personnel are actively moving material through the elevated floor-edge gate  11 , (shown as elevated floor-edge gate  11 ). This allows a delay of a predetermined period of time. According to an embodiment, the predetermined time may be two minutes. In further embodiments, the predetermined time may be any desired time that may be chosen for convenience. Once the predetermined period of time has elapsed, additional delays (such as another two minutes) can be initiated by the user, for example, by the user again manually pressing the snooze button  2 . The volume of the audible alarm  118  may be manually adjusted depending on the location of the hazard alert device  15  and the preference of the users. For example, the audible alarm may have three different loudness levels: low, medium, and high. According to an embodiment, the low, medium, and high loudness values may be chosen to be 75, 83, and 90 dB at a distance of 24 inches from the speaker. In further embodiments, any other loudness values may be chosen for convenience. 
     According to an embodiment, during the predetermined time in which the snooze mode is engaged, the flashing light  3  may continue to be illuminated to indicate that the open-gate hazard exists. According to an embodiment, when the elevated floor-edge gates,  11   a  and  11   b , and slide-latch  12  are returned to the fully closed and locked position the electrical contacts of barrier sensor  10  return to a closed position. This shuts off the flashing light  3  and silences the pulsing horn  5 , if it has not already been silenced by the snooze mode. 
     The block diagram of  FIG. 4  illustrates an embodiment in which the hazard alert device  15  includes a barrier sensor  10  and a signaling device  1 . In this embodiment, the barrier sensor  10  includes first and second sensors  101 ,  102 . The first sensor  101  includes first and second sensing elements  103 ,  104 . Each of the first and second sensors  101 ,  102  are coupled to the first processor  105  and the second processor  108 . The first and second processors  105 ,  108  form part of the controller  116 . The first sensing element  103  may be a first magnet  7 , with the second sensing element  104  sensing when the first sensing element  103  is no longer positioned within a predetermined distance from the second sensing element  104 . According to an embodiment, the predetermined distance may be ⅞ inches. In further embodiments, the predetermined distance may be any distance chosen for convenience. The first sensing element  103  may be positioned proximate (e.g., within ⅞ inches) the second sensing element  104  when the elevated floor-edge gate  11  is in the closed position. 
     According to an embodiment, for redundancy, the barrier sensor  10  may also include a second sensor  102 , which includes third and fourth sensing elements  106 ,  107 . Each of the first and second sensors  101 ,  102  are connected to the first processor  105  as well as the second processor  108 . These first and second processors  105 ,  108  form part of the controller  116 . The third sensing element  106  may be proximate the fourth sensing element  107  when the elevated floor-edge gate  11  is in the closed position and may be not proximate the fourth sensing element  107  when the elevated floor-edge gate  11  is in the open position. The first and third sensing elements  103 ,  106  may be incorporated to magnet  7  (as shown in  FIGS. 1-3 ), or utilize different magnets. Additionally, the second and fourth sensing elements,  104  and  107 , along with the first and second processors,  105  and  108 , may be housed in the receiver  17  (as shown in  FIGS. 1-3 ). 
     According to an embodiment, the first processor  105  may transmit a first signal  111  and a second signal  112  to the sensing elements and receives first and second return signals  113 ,  114  only when the first sensing element  103  is proximate the second sensing element  104  and third sensing element  106  is proximate the fourth sensing element  107 . Specifically, dual electronic, first and second processors,  105  and  108 , may interact with the barrier sensor  10  and continually compare the first and second return signals,  113  and  114 , from the redundant (dual-channel) electrical contacts of barrier sensor  10 . If there is a discrepancy between the first and second return signals,  113  and  114 , then the fault-light  8  (shown in  FIGS. 1-3 ) may illuminate to indicate a problem with at least one of the first and second sensors,  101  and  102 , or the first and second wires. The first and second processors  105 ,  108  each monitor the first and second return signals  113 ,  114 , and either the first processor  105  or the second processor  108  can place the device into a fault mode should the first and second return signals  113 ,  114  not agree with each other. 
     The signaling device  1  may then compare the first and second return signals,  113  and  114 . The signaling device  1  may further active a visible alarm  117  and an audible alarm  118  when the first and second return signals,  113  and  114 , are not both indicating the gate is in the closed position. When either or both, of the first and second sensing elements,  103  and  104 , or the third and fourth sensing elements,  106  and  107 , are separated by a greater distance than the predetermined distance (indicating the open position), the signaling device  1  may activate an alarm, for example, by illuminating a flashing light  3 , sounding a pulsing horn  5 , or both. Either the first processor  105  or the second processor  108  can activate an alarm. 
     According to an embodiment, once activated, the delay mechanism  120  is configured to silence the audible alarm  118  for a predetermined period of time, to maintain the visible alarm  117  throughout the predetermined period of time, to reinitiate the audible alarm  118  once the predetermined period of time has elapsed, or a combination thereof. 
     According to an embodiment, signaling device  1  may include a sleep mode  109  that conserves power and extends the life of the battery. For applications where the barrier sensor  10  is powered by batteries, the battery life can be extended by automatically placing the first and second processors,  105  and  108 , in a sleep mode  109  when the barrier  13  is in the closed position. The first and second processors  105 ,  108  coordinate sleep modes by using a communication link  122 . This sleep mode  109  may be interrupted momentarily at a predetermined interval. According to an embodiment, the predetermined interval may be one second (during which time a check for a closed signal from the barrier sensor  10  may be preformed). In further embodiments, the predetermined interval may be any interval chosen for convenience. The signaling device  1  may also include a low battery chirp alert to alert a user that the batteries need to be replaced. 
     In another exemplary embodiment, the elevated surface may be a loading dock. According to this embodiment, the hazard alert device  1  may include a vehicle sensor  121  communicating with the signaling device  1  such that a visible alarm  117  and/or audible alarm  118  may be provided in response to a concurrence of the gate not being in the closed position, and the vehicle not being present. 
     According to an embodiment, signaling device  1  may include a computing device such as a controller  116 . The controller  116  may be used to control and/or monitor the barrier sensor  10 . The controller  116  may comprise one or more processors and may be configured to receive software and/or firmware updates wirelessly through an associated wireless data transmitter and receiver or through a hardware connection. The controller  116  may be connected to any part of the hazard alert device  15  for central control, remote control, general monitoring, and/or data collection purposes. The wireless data transmitter and receiver may use Bluetooth, Wi-Fi, cellular, and/or any other acceptable radio frequency data transmissions and reception techniques that will be apparent to persons of ordinary skill in the relevant art(s) without departing from the spirit and scope of the disclosure. 
     Embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented as instructions supplied by a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further firmware, software routines, and instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. 
     For purposes of this discussion, each of the various components discussed may be considered a module, and the term “module” shall be understood to include at least one of software, firmware, and hardware (such as one or more circuit, microchip, or device, or any combination thereof), and any combination thereof. In addition, it will be understood that each module may include one, or more than one, component within an actual device, and each component that forms a part of the described module may function either cooperatively or independently of any other component forming a part of the module. Conversely, multiple modules described herein may represent a single component within an actual device. Further, components within a module may be in a single device or distributed among multiple devices in a wired or wireless manner. 
     The above Detailed Description of the exemplary embodiments fully reveal the general nature of the invention that others can, by applying knowledge of those skilled in the relevant art(s), readily modify and/or adapt for various applications such exemplary embodiments, without undue experimentation, without departing from the spirit and scope of the disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and plurality of equivalents of the exemplary embodiments based upon the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

Summary:
A hazard alert device, which can be battery powered or hard wired, is configured to provide a hazard alert when a gate along an edge of an elevated surface is in the open position. Upon detecting the gate is in the open position, the device produces an audible and visual alert. When the gate, disposed within a portion of the barrier, is opened to allow the movement of people and/or materials to or from the elevated surface, the device includes a snooze mode enabling the audible alarm to be silenced for a period of time. If the gate is inadvertently left in the open position, the audible alert serves as a reminder to close the gate. This device may include first and second sensors with dual channels (output signals) and dual cross-checking processors that continually compare outputs from the sensor channels to identify any defect in the sensor or wiring.