Abstract:
A barrier movement operator with a backup source of DC power is disclosed. The power supply of the barrier movement operator sends current limited DC to the backup which uses the DC to charge a battery. The battery is in circuit at all times with the barrier movement operator power supply by means of a power diode and, when an AC mains power failure occurs, DC power is sent from the battery to power the barrier movement operator.

Description:
FIELD OF THE INVENTION 
   The present invention relates to barrier movement systems and particularly to battery backup arrangements for such systems. 
   BACKGROUND OF THE INVENTION 
   Barrier movement systems, such as that disclosed in U.S. Pat. No. 6,597,138, generally are connected to mains voltage such as the 110V 60 HZ AC supplied by the local power company and use the power received to move a barrier under the command of a user. Such barrier movement systems include a power supply which converts the mains AC into DC to power electronic control circuitry and, when a DC motor is used to move the barrier, to power the DC motor. When mains power fails, such arrangements are unusable because they lack a source of stored power. 
   Known systems do exist which have a separate backup battery charging system which is connected to mains AC voltage and charge a battery when mains power is present. When mains AC power fails, the DC from the battery is switched to the barrier movement operator and used power barrier movement and to power the control circuitry for the barrier movement operator. 
   Such known arrangements require two inputs for mains AC power and two separate arrangements for converting the mains AC voltage to DC. As a result they are not integrated with the barrier movement operator they are large in size and relatively expensive. Further, they generally result in a significant time gap between failure of the mains power and the application of the backup supply which may result in an uncertain and unsafe movement of the barrier. The arrangement disclosed and claimed herein provides backup power for a barrier movement system utilizing, in part, the AC/DC conversion capability of the barrier movement system and which is connected to the power supply in a manner to provide rapid and efficient backup power. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of a barrier movement operator and battery backup arrangement; and 
       FIG. 2  is a schematic diagram of the battery backup arrangement. 
   

   DESCRIPTION 
     FIG. 1  shows a barrier movement operator  11  for controlling a motor  13  and thereby move a barrier (not shown). Barrier movement operators which control the position of a barrier are well known and not described in detail herein. The barrier movement operator  11  comprises a barrier movement controller  15  which responds to operational input signals and user generated input signals to control motor  13 . A power supply  17  received mains voltage at 110 V AC 60 HZ at input terminals  19  and converts a portion of the received voltage to DC. The barrier movement controller  15  is connected to receive DC voltage from power supply  17  via a conduction path  21  and is connected to power supply  17  via a communication path  22  so that the power supply can be monitored and controlled as needed. 
   When mains voltage is present at input terminals  19  a DC voltage is applied by power supply  17  between a conductor  23  and a conductor  25 . In the present embodiment the voltage on conductor  23  is positive with respect to conductor  25  by approximately 28V. It will be apparent that other voltage levels and polarities will also provide operational systems. The DC voltage between conductors  23  and  25  may be filtered or it may be an unfiltered full wave rectified sine wave or some DC representation inbetween. 
   Conductor  23  is connected to the cathode of a diode  27  and to a first terminal of a PTC resistor  29 . Advantageously, resistor  29  is a highly non-linear PTC device which is sometimes referred to as a self-setting fuse or a poly fuse. In the present embodiment the resistor  29  is intended to limit current from power supply  17  to conductor  31  to about 600 ma. The anode of diode  27  and a second terminal of resistor  29  are connected by a conductor  31  to one terminal of a two terminal plug  32 . The other terminal of plug  32  is connected to conductor  25  from power supply  17 . 
   Plug  32  consists of mating portions  32   a  and  32   b . Portion  32   a  remains with the barrier movement operator  11  and is configured to receive plug  32   b  from battery backup unit  39 . Plug  32  connects conductor  31  to conductor  33  and also connects conductor  25  to conductor  35 . Thus, when mains voltage is present at input  19  a DC voltage will be present between conductors  33  and  35  from power supply  17 . Battery backup  39  includes a nominally 24 volt battery  37  which is charged and maintained in a charged state by a battery charge and control circuit  41  and conductors  47  and  49 . Conductor  47  is connected to the positive terminal of battery  37  via a cut out circuit  45  which, for purposes of the present description, can be considered to be a continuous conductor from conductor  47  to battery  37 . The details of cut out circuit  45  and its functions are discussed later herein with regard to  FIG. 2 . Also included in battery backup  39  is a diode  43  providing unidirectional isolation between the positive terminal of battery  37  and conductor  33 . Diode  43  permits current flow from battery  37  toward conductor  33  and opposes such flow in the reverse direction. 
   During normal operation, while mains voltage is present at input  19 , a DC voltage is applied by resistor  29  to conductor  33  and is used to charge battery  37 . Battery charge and control arrangement  41  regulates the amount of current drawn from power supply  17  for this purpose. Should too much current be drawn by battery backup  39  (or by low resistance between conductors  25  and  31 ) PTC resistor begins to heat, causing its resistance to rise to limit the outflow of current. In an embodiment, resistor  29  may limit outgoing current to 600 ma or less due to it&#39;s highly non-linear nature. If the mains voltage at input  19  fails, the DC voltage from power supply  17  will drop and the voltage between conductors will approach the 24 volts of battery  37 . When this happens, battery  37  will act to keep 24V on conductor  33  via positively biased diode  43  and also on conductor  23  via positively biased diode  27 . Thus, battery  37  will keep significant D.C. voltage in power supply  17  when it is used to power the barrier movement operator. 
     FIG. 2  is a schematic diagram of the battery charger and control  41  and includes the cut out circuit  45  and bypass diode  43 . The battery  37 , which is the present embodiment is a rechargeable 24V battery, is connected with its positive terminal to conductor  46  and its negative terminal to conductor  49 . Control is exercised over battery charger and control  41  by a programmed microprocessor which may, for example, be a microchip PIC16F72 running at 4M HZ. Details of the oscillator circuit  53  to achieve this rate of operation are well known. Microprocessor  51  receives sensed voltage and current levels within the battery charger and control  41  and based on the sensed readings, performs functions to maintain proper operation. 
   Regulated power to control the operation of battery charger  41  is provided by a power supply circuit  57  in response to input power from conductor  33  and conductor  47  via diodes  59  and  61  respectively. The dual connection of input power to the power supply  57  permits selective powering of the battery charger and control  41 . The voltage on conductor  47  which may be from the battery charging circuit  63  or from the battery  37  or both is sensed by a voltage divider network  65  and applied to microprocessor  51  via a conductor  66 . The voltage input on conductor  33  is similarly sensed by a voltage divider  67  and applied to microprocessor  51  via a conductor  68 . The charge current being provided to battery  37  is sensed from the voltage developed by a resistor  70  which voltage is applied to microprocessor  51  via an op-amp  72  and a conductor  73 . Similarly the current being drawn from battery  37  is detected as a voltage across a resistor  77  which voltage is applied to microprocessor  51  via an op-amp  75  and conductor  76 . Microprocessor  51  receives the signals representing various sensed parameters at analog inputs and controls operation in accordance with programming. 
   Battery charger  63  includes a series connected power FET  79  the conduction state of which is controlled by microprocessor  51  via a conductor  80  and driver transistor  81 . The FET  79  is controlled in the pulse width modulation (PWM) mode. Control pulses are sent from microprocessor at a predetermined rate e.g., 1 KHZ and the width of the control pulses is increased or decreased depending on the charging needs of battery  37 . Cut out circuit  45  comprises a relay  83  which is controlled by microprocessor  51  to connect or disconnect battery  37  from the battery charging and control circuit  41 . In the described embodiment, relay  83  comprises two coils  84  and  85  which are selectively enabled by microprocessor  51  to connect or disconnect the battery. The relay  83  shown must be actively pulsed to switch from one state to the other so that, should power be lost the relay will remain in the last state it was commanded to be in. The battery  37  is connected by relay  83  in response to a pulse on conductor  87  via transistor  88  and it is disconnected by a pulse on conductor  89  via a transistor  90 . A user is advised as to the state of charging and control circuit  41  by three separately controlled LEDs  91 ,  92  and  93  which display the colors red, green and yellow respectively and by an audible signaling device  95  which in the present example is a buzzer. 
   When plug  32   b  ( FIG. 1 ) is plugged into plug  32   a  and power is being provided between conductor  33  and  35  from power supply  17 , the battery charge and control circuit  41  will enter, or remain in, the battery charge mode. In the battery charge mode, the battery voltage and battery charging current are sensed and a selected PWM signal is sent to FET  79  to properly charge the battery  37 . While the battery is being charged the green LED  92  is flashed. When the sensed battery voltage achieves a predetermined level, microprocessor  51  reduces the PWM signal to a maintenance amount and green LED  92  is controlled to provide an apparently continuous on light. As is apparent, the relay  83  is in the closed state during battery charging and maintenance. Should the microprocessor  51  detect a faulty battery by excessive charging current or battery voltage above a predetermined threshold, the battery will be removed from the circuit by controlling cut out  45  to open circuit. 
   When the charging and control  39  is in the charging or maintenance state and mains power fails eliminating the ability of power supply  17  to produce DC power, current will begin to flow from battery  37  via diode  43  and conductor  33  back to the barrier movement operator  11 . This transition is automatic and done without the need for control by microprocessor  51 . The yellow LED  93  is enabled when power is being taken from battery  37  as will be manifested by a lower voltage at conductor  33  than at conductor  47 . Should mains power be restored to barrier movement operator  11  the voltage on conductor  33  will rise and microprocessor  51  will turn off yellow LED  93  and again enter the charge mode. 
   When mains power remains off and the barrier movement operator  11  is moving the barrier, the increase in battery current will be sensed and buzzer  95  will be turned on to audibly advise the user that battery power is controlling present operation. Alternatively, the buzzer may be intermittently enabled during the entire time that the system is under battery power, but such is often determined to be a nuisance. While running on battery power the battery voltage is compared to a Voltage Dropping threshold and should battery voltage drop below it, the yellow LED  93  will be flashed and optionally the buzzer  95  will be enabled. Lastly, should battery voltage diminish to a Low Battery threshold, cut out  45  will be opened to protect the batteries from over discharge. The resumption of mains power will automatically restore the described arrangement to the charging state. 
   Several user protection mechanisms are built into the operation of the system. For example, should plug portions  32   a  and  32   b  be separated and conductors  31  and  25  be shorted, current will be limited to a small value by non-linear resistor  29 . Also when unplugging occurs, no charging or discharging current will be detected by microprocessor  51 . When this occurs, relay  83  is opened so that no battery power is available between conductors  33  and  35  so that improper connection of conductors  33  and  35  will be harmless.