Abstract:
Methods and apparatus for detecting obstructions in the path of a movable barrier are disclosed. Embodiments are included which advantageously combine edge sensing contact detectors and non-contact detectors such as photo eye detectors. Relay logic is also described for controlling the response of a movable barrier operator to input signals including input signals from contact type and non-contact obstruction detectors.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a utility patent based on U.S. provisional application Serial No. 60/396,071, filed Jul. 16, 2002, which is incorporated herein by reference in its entirety. 
     
    
     
         [0002]    The present invention relates to safety systems for the movement of movable barriers.  
           [0003]    Movable barrier control systems such as door, garage door, sliding gate, swinging gate, etc. generally include some form of obstruction detection. Such detection may include contact edges or non-contact sensing such as infra-red (IR) optical devices ultra-sonic, Radio Frequency, etc. to detect the presence of an obstruction in the path of the barrier and control the movement of the barrier based on such a detected obstruction. A need exists for improved arrangements for obstruction sensing and resultant barrier movement. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0004]    [0004]FIG. 1 represents the basic safety and control structure of an automatic sliding gate;  
         [0005]    [0005]FIG. 2 is a block diagram of a combined IR and physical contact obstruction detection system for a movable barrier;  
         [0006]    [0006]FIG. 3 is a block diagram on IR obstruction sensing system.  
         [0007]    [0007]FIG. 4 is a schematic diagram of relay logic responsive to the contacts of a voltage sensing relay to control barrier movement. 
     
    
     DESCRIPTION  
       [0008]    [0008]FIG. 1 illustrates an automatic sliding gate arrangement for illustration purposes. The principles taught regarding the operation of the FIG. 1 arrangement are easily applicable to other types of automatic barrier movement arrangements. In FIG. 1 pylons  101  and  103  define a gate opening  105  in a fence  107 . A control unit  111  which includes a control circuit  113  and a motor  115  responds to user requests to open and close a gate  109  by sliding it across the gate opening  105 . The user requests may arrive in the form of signals from a push button key-pad or as coded rf signals which are received by the control circuit  113 , decoded and approved or not, as is well known in the art.  
         [0009]    Before a barrier begins to move and during movement it is advantageous to identify whether an obstruction is present which may be contacted by the moving barrier. The arrangement of FIG. 1 includes an IR transmitter  119  and an IR receiver  121 . As can be readily seen other types of non-contact sensors such as ultra-sonic, optical etc. may be employed in place of the IR transmitter and receiver. Under the control of control circuit  113  transmitter  119  directs an IR beam to receiver  121  which detects the presence or absence of a received IR beam to identify obstructions in the path of the barrier. The apparatus of FIG. 1 also includes contact type obstruction sensors  123  and  125  which identify when the barrier physically contacts an obstruction during closing ( 123 ) or during opening ( 125 ). As shown in FIG. 2 the contact obstruction sensors comprise a pair of spaced apart conductors  129  and  131 . When the obstruction detector deforms due to contact with an obstruction, the conductors  129  and  131  make contact thereby changing the manner of current flow through the detector. Such a change in current flow indicates, in a manner discussed below, that an obstruction has been contacted.  
         [0010]    [0010]FIG. 2 is a block diagram of the interaction of control circuit  113  and the sensors  123 ,  125 ,  119  and  121  to control barrier movement. Control unit  111  includes a voltage source such as transformer secondary  151  which supplies a voltage of, for example 24 vac, between conductors  153  and  155 . Conductors  153  and  155  are connected to an IR obstruction arrangement  157  which represents, in part, IR transmitter  119  and IR receiver  121  and a controller  159 . When powered from the voltage source  151  an IR beam is sent and received, as discussed above, and receiver  121  sends a signal to control  159  to indicate reception of such an IR beam or not. When controller  159  is notified that an IR beam is being received, normally open switches  161  and  163  are closed to pass the voltage between conductors  153  and  154  on to subsequent apparatus. Alternatively, when no IR beam is received by receiver  121  switches  161  and  163  are opened to their normal state and no voltage is applied to the conduction path beyond obstruction detector  157 . The voltage between conductors  153  and  155  is passed on to an optional IR sensor  165  which operates in the same manner to close or open the voltage path depending on whether an obstruction is sensed. The optional IR detector  165  is not employed in FIG. 1. When other types of non-contact sensors are used they function to close contacts such as  161  and  163  when no obstruction is detected and to open the contacts in the case of system failure or detected obstruction.  
         [0011]    The conduction path proceeds beyond detector  165  to the contact edge sensors  123  and  125  via a resistor  167 . Resistor  167  is used to control excessive currents when conductors e.g.,  129  and  131  contact one another. The conduction path continues through edge detectors  123  and  125  to a voltage sensor  169  which is shown in FIG. 2 as a relay coil EC 1 . Relay EC 1  includes a normally open contact pair  171  the state of which is sensed by control  113 . Whenever the contacts  171  are opened control circuit  113  directs motor  115  to move the barrier to a safe position. Such a safe position in the case of an overhead door is the open position. In the case of gate  109  the safe position may be backing off the obstruction, or reversing to maximum travel in the opposite direction that the gate was traveling when the obstruction was sensed. Should an obstruction be sensed while the gate is retreating from a prior obstruction, stopping the gate is considered to be the safe position.  
         [0012]    As is apparent from FIGS. 1 and 2 and the preceding description, whenever an obstruction is sensed or a failure occurs along the conduction path from voltage source  151  to sensor  169 , control  113  will sense such and control motor  115  to move the barrier  109  to a safe position. Alternatively, as long as voltage sensor  169  continues to sense a predetermined voltage from source  151 , control  113  will control the motor to move the barrier  109  in accordance with user or other commands.  
         [0013]    [0013]FIG. 3 shows an obstruction sensing arrangement similar to that shown in FIG. 2 except without the contact sensors  123  and  125 . The dropping resistor  167  may be removed from the embodiment of FIG. 3, and relay  169  replaced with a 24V relay, because no current carrying parts of FIG. 3 require the protection of such a resistor.  
         [0014]    [0014]FIG. 4 shows a relay logic controller for use in control circuit  113 .  
         [0015]    The drawings and the foregoing descriptions are not intended to represent the only forms of the invention in regard to the details of its construction and manner of operation. Changes in form and in the proportion of parts, as well as the substitution of equivalents, are contemplated as circumstances may suggest or render expedient; and although specific terms have been employed, they are intended in a generic and descriptive sense only and not for the purposes of limitation, the scope of the invention being delineated by the following claims.