Abstract:
A remote-controlled motor-driven drum is provided to wind and unwind a cord which holds a self-balancing sign carrier. The sign carrier, which has telescoping rails, is adjustable in width. Its center rail includes two sheaves to receive the cord and lead it from the drum back to an end secured to the ceiling. Rotation of the drum raises and lowers the sign carrier and a sign carried by it. The sheaves on the carrier also serve to make the unit self-balancing. The motor responds to actuating signals for raising and lowering the sign and to safety features. Safety features include a limit switch which stops the motor when an object gets in the way, an overload control which stops the motor if excessive weight is detected, and the use of the motor for braking.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of application Ser. No. 08/408,934, filed Mar. 23, 1995 now U.S. Pat. No. 5,529,274, the contents of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a system for suspending signs, and more particularly to a system for suspending signs and for readily raising and lowering them. The system is useful in retail stores. 
     Often a retailer desires to hang, or change, a sign hanging from a particular location of his store. Often these signs are placed in locations readily viewable to consumers, such as near the ceiling. To hang or change a sign involves obtaining and using a ladder, or otherwise getting access to the ceiling area. Beyond the logistical problems of obtaining access, persons who either climb on the ladder or enter into the ceiling area encounter increased risk of injury. 
     There is a need for a suspension system for signs that does not require persons hanging or changing signs to reach the hanging location of the sign so that problems of access and injury are reduced. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a sign suspension system that substantially obviates one or more of the problems due to disadvantages and limitations of the prior art. 
     In accordance with the purpose of the invention, as embodied and broadly described, the invention utilizes a remote-controlled motor-driven drum as a winder, to wind and unwind a cord which is secured between a ceiling fixture and the drum and is holding a sign carrier. In an alternative embodiment, the loose end of the cord is secured to the extension of the motor operated drum unit. The sign carrier, which has telescoping rails, is adjustable in width, so as to hold different size signs. Its center rail includes two equally-spaced sheaves to receive the cord and lead it from the motor-driven drum to an end secured to the ceiling. Thus, motion of the drum serves to raise and lower the sign carrier and a sign carried by it. The equal spacing between the sheaves on the carrier and between the ceiling fixture exterior of the motor operated drum unit and the drum serve to make the unit self-balancing. 
     The user attaches a sign to the carrier wherein it is in its lowered position and then uses the motor to raise the sign and carrier to the ceiling. The motor, which is reversible, is remotely controlled either by wires leading between the motor and a switch, by radio control (with a control similar to that used on a garage door), or by using an infra red transmitter directed to an infra red receiver associated with the motor. Reversing the motor, of course, serves to lower the sign so that it can be replaced. 
     Safety features included are a limit switch at the motor unit, which stops and/or reverses the motor when an object gets in the way; a slip clutch which prevents overload of the motor; an overload control which stops the motor from raising the sign if excessive weight is detected; and use of the motor for braking. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed. 
     The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, and illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the Figures: 
     FIG. 1 illustrates the system for suspending a sign including a raised sign and a user, holding a remote control unit, below the sign; 
     FIG. 2 illustrates the sign lowered so that the user can access the sign; 
     FIG. 3 illustrates details of the system of FIGS. 1 and 2; 
     FIG. 4 illustrates an enlarged view of a portion one of the sheaves of FIG. 3; 
     FIG. 5 illustrates a cross-section of the sheave of FIG. 4 along line  5 — 5  of FIG. 4; 
     FIG. 6 illustrates a portion of the sign-carrying rails and of one of the associated sheaves of FIG. 1; 
     FIG. 7 illustrates a front elevation, partially broken away, of the motor-drum section FIG. 1; 
     FIG. 8 illustrates an alternative embodiment of a motor-drum unit including an attachment point according to the present invention; 
     FIG. 9 illustrates an enlarged portion of FIG. 3 including a limit switch; 
     FIG. 10 illustrates a plurality of motor-drum units of FIG. 1 controlled by a remote control within a limited cone of reception; 
     FIG. 11 illustrates an alternative embodiment of a sign support according to the present invention; 
     FIG. 12 illustrates a block diagram of the motor-drum unit; and 
     FIG. 13 illustrates a flow chart showing the operating cycle of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A system for suspending a sign includes a sign, supporting rails, a cord, and a motor unit. As embodied herein and referring to FIG. 1, the system for suspending a sign includes the sign  1 , the supporting rails  3 , the cord  23 , and the motor unit  43 . 
     The supporting rails  3 , that includes center main rail  5 , frame  29 , and side rails  7  and  9 , support sign  1 . The cord  23  threads from an attachment member  41  through center main rail  5  into motor unit  43 . Motor unit  43  mounts to a support structure  19 . 
     FIG. 2 illustrates the system of FIG. 1 in a down position, that is, the cord  23  extended from the motor unit  43  so that the sign  1  is lowered. 
     FIG. 3 illustrates a detailed view of the sign  1  in an up position. The cord  23  extends from attachment member  41  through an opening  6  in center main rail  5  and around a sheave  25  to another sheave  27  and exits the center main rail  5 . After exiting the center main rail  5 , the cord  23  enters the motor unit  43  and attaches to a drum  53  located within motor unit  43 . 
     FIG. 4 provides a detailed view of the sheave arrangement of FIG.  3 . The cord  23  enters the opening  6  in center main rail  5 , passes around the sheave  25 , and travels to sheave  27 , that has a similar configuration, but mirrored with respect to sheave  25 . 
     FIG. 5 illustrates a section across line  5 — 5  of FIG.  4 . The cord  23  passes through opening  6  and around a drum  31 , that is part of sheave  25 . Frame  29  provides a mounting location for drum  31 . Slots  33  in frame  29  of rails  3  provide a location in which side rails  7  and  9  may slide. The side rails  7  and  9  have T-shaped members  10  which telescope into slots  33 . Holding bolts  11  lock the T-shaped members  10  in position in frame  29  and thumb screws  13  hold sign  1  in the rails  7  and  9 . 
     FIG. 6 provides another view of the portions just described showing how the T-shaped members  10  slideably attach into slots  33 . 
     FIG. 7 illustrates an end view of motor unit  43 . A control unit  45  connects to a reversible motor  49 . A reduction gear  51  connects reversible motor  49  to drum  53 . An optional antenna  47  mounts to the bottom of the motor unit  47 , although its actual placement is a design choice. 
     When hanging, attachment member  41  secures one end of the cord  23  while the other end is wrapped around drum  53  as illustrated in FIG.  3 . Sheaves  25  and  27  are configured to be centered on the sign for self-balancing. The threading of the cord  23  around the sheaves  25  and  27  allow the sign  1  to maintain balance as the cord is extended out of and retracted into motor unit  43 . Preferably, the spacing between the sheaves  25  and  27  is substantially the same as the spacing between the attachment member  41  and the drum  53 , allowing the sign to balance more readily. 
     FIG. 8 illustrates an equally preferred embodiment in which attachment member  41  is located on motor unit  43 . In this embodiment, motor unit  43  extends a length at least equal to the separation distance between sheaves  25  and  27 . The specific location of attachment member  41  on motor unit  43  is a design choice, but the distance between the attachment member  41  and the point where cord  23  exits motor unit  43  is preferably equal to the distance between sheaves  25  and  27 . Less preferred are distances that are not equal because they create horizontal stresses on the sheaves  25  and  27 , the attachment point  41 , and the exit location of cord  23  from the motor unit  43 . FIG. 8 illustrates attachment member  41  located on one end of motor unit  43 , however, equally preferred locations include the sides and the bottom of motor unit  43 . 
     The user activates control circuit  45  (FIG. 7) with remote control unit  15  (FIG. 1) in combination with antenna  47  in a manner similar to radio-controlled garage doors. Alternatively, the control unit  15  can be wired directly to the control circuit  45 , or be operated by an infra-red signalling system. Preferably, the control unit  15  has at least buttons for off, forward, and reverse. 
     In operation, the user activates the motor  49  to rotate drum  53  to extend the cord  23 , lowering the rails  3  from the ceiling. The user adjusts main rail  5  and side rails  7  and  9  to provide a total length equal to the width of the sign  1  to be displayed (with side rails  7  and  9  being extended equal amounts) and then tightens the holding bolts  11 . The user inserts the sign  1  between the rail sections, threads thumb screws  13  through the sign and tightens them. The user then operates motor  49  in the opposite direction, causing the motor to rotate drum  53  so that the cord  23  wraps around drum  53 , and thus raising the sign  1 . The sign self-balances and hangs horizontally at any desired height. 
     A limit switch  61 , illustrated in FIG. 9, is preferably positioned on the lower surface of the motor unit  43 , proximate to cord  23 . An arm  63  pivotally connects to the motor unit  43  and carries a ring or loop  65  which surrounds the cord  23 . When the arm  63  is moved upwardly by a user&#39;s hand inadvertently getting in the way or by the top of the sign  1  or the rails  3 , arm  63  actuates the limit switch  61  and reverses the motor  49 . 
     The limit switch  61  serves two purposes: it will prevent the user&#39;s hand from being accidently caught up on and torn by the cord  23  (carrying the sign); and it prevents the sign  1  and the rails  3  from hitting the motor unit  43 . When actuated, the motor  49  instantly reverses and extends the cord  23  about one foot. Alternatively, the limit switch  61  causes motor  49  to stop instead of reversing direction. 
     FIG. 10 illustrates an infra red control system, that can separately control one or more suspended signs  1 . FIG. 10 illustrates two such sign suspension systems. Each of the motor units  43  preferably carries an infra red detector  71  on its lower surface. Preferably, the detectors receive only within a limited cone of reception  73 . The cone of reception  73  is preferably centered about a vertical axis and can be dimensioned such that it has a radius of about ten feet at a distance from the detector approximating the level at which the operator will hold the actuating infra red transmitter  77  from the motor unit  43 . Thus, for example, if the motor unit is mounted to a ceiling fifteen feet high and the operator holds the transmitter at approximately chest level (three feet from the floor), then the cone should preferably have a ten foot radius at about twelve feet from the detector  71 . Infra red transmitter  77  is preferably a directional transmitter. As a result, the user can readily control one sign at a time by holding the transmitter within the cone of reception  73  of the desired sign and aiming it at the detector  71  on that sign. The transmitter should have a coded beam, i.e., sending one code to operate the motor in forward and a different code to operate the motor in reverse, the codes being selected by pressing either a forward button  79  or a reverse button  81  on infra red transmitter  77  as illustrated in FIG.  10 . 
     FIG. 11 illustrates another preferred embodiment for supporting the sign  1 . In this embodiment, sheaves  25  and  27  are mounted on a supporting member  98 . Supporting member  98  is a generally upside down U-shaped member having a plurality of pairs of holes  99  in the extending sides of the U-shape, each pair consists of one hole on one side and a corresponding hole on the other side. A user inserts sign  1  into the U-shape and inserts a clip  100  into each of the holes on one side so that they extend through to the other side to secure the sign  1 . 
     Supporting member  98  is preferably aluminum or plastic and made by extrusion. Any material effective to provide support to a sign is also preferred and may be made by any manufacturing process. 
     Clips  100  are preferably a dart clip or a christmas tree clip, but may be any type of clip effective to extend through the U-shape and secure the sign  1  to the supporting member  98 . One skilled in the art would recognize many equivalents of this type of clip. 
     FIG. 12 presents a block diagram of a portion of the system according to the invention and includes a microprocessor, current sensors, a power supply, forward/reverse relays, an on/brake relay, an infra red (IR) decoder, a detector pre-amplifier, a limit switch, a remote control unit, and a motor. As embodied herein and referring to FIG. 10, this portion includes microprocessor  89 , current sensors  93 , a power supply  91 , forward/reverse relays  95 , an on/brake relay  97 , an IR decoder  87 , a detector/pre-amplifier  85 , limit switch  61 , remote control unit  77 , and motor  49 . 
     The IR detector/pre-amplifier  85  connects to the IR decoder  87  that in turn connects to the microprocessor  89 . Limit switch  61 , on/brake relay  97 , forward/reverse relay  95 , and current sensor  93  also connect to microprocessor  89 . Power supply  91  connects to forward/reverse relay  95  and to current sensor  93 . Forward/reverse relay  95  connects to on/brake relay  97  that in turn connects to motor  49 . 
     To raise or lower a sign, a user presses the forward  79  or reverse  81  button on infra transmitter  77 , sending a directional beam of infra red light, encoded for either forward or reverse, to the infra red detector  71  at the motor-operated drum unit  43 . The IR detector/pre-amplifier detects and amplifies the signal and passes it to IR decoder  87 . IR decoder  87  determines whether the signal indicates forward or reverse and passes the determination to microprocessor  89 . The microprocessor  89  then sends the appropriate signals to the forward/reverse relay  95  and to the on/brake relay  97 , resulting in operation of the motor  49  in the desired direction. 
     Although illustrated as infra red, equally preferred is any type of signalling system that can communicate forward or reverse to the motor unit  43 . 
     Power supply  91  provides power for motor  49  through the forward/reverse relay  95  and the on/brake relay  97 . 
     When relay  97  acts as a brake, it electronically shorts the motor  49  terminals together, causing the motor  49  to brake and increase the holding power in the stop mode. 
     Current sensor  93  detects the amount of current passing from the power supply  91  to the motor  49  and sends a corresponding signal to the microprocessor  89 . If the sign  1  is too heavy or someone pulls on the sign while it is being lifted, an overload is detected and the microprocessor  89  instantly stops the motor  49 . The motor  49  will not then move in the up direction until it is reversed for a moment to reset the circuitry. The extent of overload required to actuate this feature can be adjusted for sign weight such that any amount over this adjustment will trip the overload feature. Preferably, the range for the sign weight is from about 2 pounds to about 10 pounds. The actual weight, however, is not critical to understanding the operation of the invention, since it may be adjusted for any desired weight. 
     The limit switch  61 , described above with reference to FIG. 8, is also connected to the microprocessor  89 , and additionally controls the motor  49 . When the limit switch  61  is actuated, the motor reverses direction for a moment, preferably 600 milliseconds, and stops. A user must release whichever button was pressed before the motor  49  can be operated again. 
     FIG. 13 illustrates the flow chart of the operation of the sign suspension system including its protective features, preferably, under the control of microprocessor  89 . Initially, at the start  101 , the motor is off. At block  103 , the motor is off and the system waits for a signal from control  77 . The system moves to decision block  105  and checks for a forward signal. If the determination is yes, a forward signal is present and the system moves to block  109  and activates motor  49  in the forward direction to extend the cord  23 . Since the drum  53  is continuous, if for some reason, the user extends the cord  23  past its maximum, then the motor will be operating in a forward direction but the cord  23  begin to wrap around the drum  53  and start retracting. Thus, the operation according to the flow chart in FIG. 13 operates in a similar manner whether the cord is extending or retracting when the motor is operating in the forward direction. For the purposes of this description, it is assumed that forward initially operates the motor to extend the cord  23 . 
     The system then moves to decision block  111  and checks the position of the limit switch  61 . If the limit switch  61  is on, then the system moves to block  117  and reverses the motor  49  to extend the cord  23 . In this instance, forward was retracting the cord  23 . The system moves to block  119  and waits 600 ms, allowing the motor  49  to extend about a foot of cord  23 . After 600 ms, the system moves to block  145  and stops the motor  49 . After waiting 200 ms in block  147 , the system checks to determine whether both the forward button  79  and the reverse button  81  are off. If the determination is no, then the system loops back to block  145 . If the determination is yes, then the system loops back to block  103 . 
     If, at decision block  111 , the system determines that the limit switch  61  is off, then the system passes to decision block  113  and determines whether an overcurrent situation is present. If no, then the system passes to decision block  115  and determines whether the forward button  79  is still on. If no, the system passes to block  145  and control occurs as described above. If yes, the system passes to block  109  and control occurs as described above. 
     If the system determines in decision block  113  that an overcurrent situation is present, the system passes to block  135  and stops the motor  49 . The system then passes to decision block  137  and determines whether the reverse button  81  is on. If the reverse button  81  is off, the system loops back to block  135  and continues looping until the reverse button  81  is pressed. If the system determines that reverse button  81  is on in decision block  137 , the system passes to block  121  and activates the motor  49  to extend the cord  23 . The system then determines whether the limit switch  61  is on in decision block  123 . If the limit switch  61  is on, the system passes to block  129  and reverses the motor  49 . The system then passes to block  131  and waits for 600 ms, allowing the motor to extend the cord  23  about one foot. After waiting the 600 ms the system passes to block  145  and continues as described above. Even if the cord is extended to the maximum and rewinds in the opposite direction on the rotating drum  53  all safety features remain unchanged. Cord  23  will still extend when the limit switch  61  is activated. 
     If the system determines at decision block  123  that the limit switch  61  is not on, then the system passes to decision block  125  where it checks to determine whether an overcurrent situation is present. If an overcurrent situation is present, the system passes to block  139  and stops the motor  49 . After stopping the motor  49 , the system passes to decision block  141  to determine whether the forward button  79  has been pressed. If not, then the system loops back to block  139  and continues looping until the forward button  79  is pressed. Once the system determines in decision block  141  that forward button has been pressed, it moves to block  109  and progresses as described above. 
     If the system determines at decision block  125  that an overcurrent situation is not present, then the system moves to decision block  127  and determines whether the reverse button  81  is still on. If the system determines that the reverse button  81  is off, then the system passes to block  145  and continues as described above. If the system determines that the reverse button  81  is still on, then the system returns to block  121  and continues as described above. 
     If the system determines in decision block  105  that the forward button  79  is not on, then the system passes to decision block  107  and determines whether the reverse button  81  has been pressed. If the reverse button  81  has not been pressed, then the system loops back to block  103  and continues as described above. If the system determines that the reverse button  81  has been pressed, then the system passes to block  121  and continues as described above. 
     Those skilled in the art will immediately realize various modifications and variations that can be made to the sign suspension system of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided that they come within the scope of the appended claims and their equivalents.