US3783556A

US3783556A - Door control system providing automatic delayed door reversal

Info

Publication number: US3783556A
Application number: US00271511A
Authority: US
Inventors: J Cook
Original assignee: Telectron Inc
Current assignee: Telectron Inc
Priority date: 1972-07-13
Filing date: 1972-07-13
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08

Abstract

A door control system for controlling a door which is operated by an instantaneously electrically reversible motor is disclosed. When a door open sensor is actuated while the door is closing, the control system stops the door and after a predetermined delay energizes the motor to reopen the door fully. If an emergency reverse sensor is actuated while the door is closing, the drive motor is instantaneously reversed to stop the door in a minimum time and immediately reopen it.

Description

United States Patent [191 f 1111 3,783,556

Cook Jan. 8, 1974 [54] DOOR CONTROL SYSTEM PROVIDING 3,001,038 9/1961 Gessell 49/27 X AUTOMATIC DELAYED O REVERSAL 3,510,982 5/1970 Purdy 49/25 [75] Inventor: John F. Cook, Milwaukee, Wis.

Primary Examiner-J. Karl Bell [73] Assigneez glelectron, Inc., Fort Lauderdale, Atwmey Eric P schemn et [22] Filed: July 13, 1972 21 Appl. No.: 271,511 [57] I ABSTRACT A door control system for controlling a door which is operated by an instantaneously electrically reversible [52] US. Cl 4 9/25, 49/27,:99//236(2 motor is disclose d when a door p sensor is actw [51] Int Cl E05 15/16 .ated while the door is closing, the control system stops [58] Fieid I 263 the door and after a predetermined delay energizes the motor to reopen the. door fully. If an emergency 5 6] i Cited the drive motor is instantaneously reversed to stop the UNITED S A S PATE TS door in a minimum time end immediately reopen it. 2,758,836 8/1956 Purdy 49/27 x 8 Claims, 3 Drawing Figures reverse sensor is actuated while the door is closing,

DOOR CONTROL SYSTEM PROVIDING AUTOMATIC DELAYED DOOR REVERSAL BACKGROUND OF THE INVENTION nisms which provide for reversal of the doors movement. These operators are of one .of two types. The first type are those which employ instantaneously reversible motors and in which the motor drive is instantaneously reversed in response to a door open signal. These systems provide maximum safety where the door opening sensor is a safety edge on the bottom of the door, since they stop the door as quickly as possible and reopen it immediately to free any object which may have been struck by the door. However, these systems cause severe strain on the door and the door operating linkages because of the tremendous accelerations involved. Thus, these door operators cause unnecessary wear and tear on the door and its operating mechanisms for nonemergency reversals.

The second type of door operatorsare those which stop the door in response to a sensor signal and reverse the motor controls so that on the subsequent motor actuation it will reverse the direction of movement of the door. These systems reduce the stresses on the doors and their operating linkages, but require a subsequent actuation of the motor which is not automatically provided. In addition, they are not as safe in emergency situations as are the instantaneously reversing door mechanisms.

OBJECTS A primary object of this invention is to provide a 40 SUMMARY This invention accomplishesthe above and other objects which will become apparent hereinafter by providing a door reversing means which controls the reversal of the doors movement in accordance with what sensor provides the door reversing input.

The door reversing means comprises a delay selection relay in one position of which the door opens immediately in response to a door open signal and in the other position of which the door opens only after a delay period controlled by the delay timer. An emergency reverse relay by-passes the delay timer and opens thecircuit which energizes the door in the closingdirection while simultaneously causing the motor to be energized in the door opening direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a garage door with the door control system installed.

FIGS 2a and 2b when placed side by side form acircuit diagram of the door control mechanism, these figures will ;be referred to collectively as FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The general environment in which the door control ler of the invention is employed is shown in FIG. I. A garage building 10 has a vehicular'door 12 for control ling access to the garage along a vehicular travel lane 14 which passes through the doorway. The door is shown as moving in a vertical direction to open and rides on tracks or guide rails I6 which are attached to or suspended from the garage roof. An instantaneously electrically reversible door propulsion motor 18 drives a door operator 24 which moves the door up or down in accordance with the direction of rotation of the motor 18. The doorcontrol system of this invention is shown as enclosed within a box 28 mounted on the garage wall. Portions of the system which are mounted outside ofthebox are wired to the circuitry within the box. A presence sensor 30 which is shown as photocell 30 which may be any photoresponsive device having the proper characteristics is mounted inside the garage adjacent to the door and positioned to receive a light beam from a light source 32 mounted on the other side of travel lane 14 and within the garage. The light source provides a light beam which is directed across the travel lane at photocell 30. Thislight beam. is interrupted .by an object passing through the doorway.

A treadle switch 36 is operated by a vehicle sensing device such as a driveway bell hose 34 and provides a sensor signal to the control'system indicating that a vehicle is positioned in the travel lane to enter the door way. An emergency reverse sensor such as safety edge 38 is mounted on the door to operate an emergency reverse switch 39 in the event that an object is obstruct ing the path of the door.

A circuit diagram of the control system is provided in FIG. 2; it, is noted that conductors 260,264,2,268,27ID,272,274 and 2'76 continue from FIG. 2a into FIG. 2b. The diagram illustrates the circuit as it is with the door closed and the control system power on. References to the positions of switches as being normally open or normally closed are made with reference to this diagram, that is with the control system energized and the door closed.

.A motor energizing door opening relay 40 controls.

the energization of motor winding 2% which drives the motor in the direction which opensthe door 112. Relay. 40 has an operating winding 42 which controls the operation of two normally open single pole, single throw (SPST)

switches

46 and 54. Upon energization of the relay, switch 46 energizes motor winding 20 to open the door. Switch 54 establishes a holding circuit to maintain relay 41th in its operated condition until the door is. fully opened, at which time the door opens an open limit switch 60 which de-energizes relay 40 by breaking the path from operating winding 62 to the ground conductor 268.

Treadle switch 36 operates a treadle relay to initiate a dooropening cycle. Relay 70 has an operating winding 72 which controls the operation of two, single pole,

double throw switches

76 and 82. The moving contact of switch 76 is connected to conductor 266 which is connected to the hot side of the power supply through manual stop switch 254 and power on-off switch 240. Hereinafter the conductor 266 will be referred to as being the hot side of the power supply, since it is hot at all times when the control 'system is turned on, except when the manual stop switch is depressed. The normally open contact of switch 76 is connected to an open signal conductor 260. The normally closed contact of switch 76 is connected to switch 184 which forms part of a close presetting relay holding circuit which will be described hereinafter.

Switch 82 controls some of the connections internal to a photorelay operating circuit 230 which controls the operation of a photorelay 210 in accordance with the condition of the light beam which is sensed by photocell 30.

Upon actuation, switch 76 of treadle relay 70 connects conductor 260 to power supply bus 266.

Conductor 260, is connected to a normally closed single pole, single throw, switch 144 and to the operating winding 122 of a reopen delay relay 120 which forms a part of the door reversing means 100. Door reversing means 100 is comprised of the reopen delay relay 120, a delay timer 102 and an emergency reverse relay 130. Relay 120 controls two normally open single pole, single throw switches, 124 and 126. Switch 124 when closed by actuation of relay 120 forms a holding circuit to maintain the relay actuated. Switch 126 when closed by actuation of relay 120 connects the output of the delay timer to the operating winding 42 of relay 40 to energize motor winding to open the door.

Delay timer 102 is a single pole, single throw thermal delay switch having a stationary contact 104, a common terminal-106, a heater 108 and bimetallic moving contact 1 10. Heater 108 and bimetallic contact 110 are both connected to the common terminal 106. The other end of heater 108 is connected to the grounded side of the power supply. When heated by heater 108, bimetallic moving contact 110 bends into contact with stationary contact 104 to connect terminal 104 to common terminal 106. Terminal 104 is connected to switch 126 and forms part of the energization circuit for relay 40 when the thermal delay switch is closed. Closure of the thermal delay switch 102 while relay 120 is energized connects operating winding 42 of relay 40 to the hot side of the power supply, thus energizing the relay to operate motor 18 to open the door.

Switch 144 is operated by the operating winding 142 of relay 140. This relay maintains switch 144 open at all times except when a close limit switch 62 is open. The close limit switch 62 is open only when the door is fully closed. When switch 144 is closed, the re-open delay relay is by-passed and relay 40 is actuated upon conductor 260 being connected to power buss 266. Thus, when the door is fully closed, it begins to open immediately upon actuation of treadle relay 70 by treadle switch 36.

The emergency reverse relay 130 controls two normally open single pole, single throw switches 134 and 136. Switch 136 by-passes the delay system to connect operating winding 42 of a relay 40 directly to the hot power line bus 266. Switch 134 when closed acmates treadle relay 70 to operate switch 76 to de-energize motor winding 22 which energizes the motor to'close the door.

An interlock relay 160 controls two single pole, single throw switches 164 and 166. Switch 164 is normally open, while switch 166 is normally closed. Normally closed switch 166 connects a manual door close switch 248 to the hot side of the power supply. Switch 164 connects conductor 260 to the normally open contact of a photorelay switch 214 which will be discussed hereinafter. The interlock relay serves to prevent breaking of the light beam from causing the door to open, when the door is fully closed.

In order to energize the motor to close the door, two relays must be concurrently energized. These are a close preset relay 180 and the close door motor energizing relay 200. Close preset relay 180 controls two single pole, single throw switches, 184 and 186. Switch 184 is normally open, while switch 186 is normally closed. When switch 186 is opened by actuation of relay 180, it breaks oneof the holding circuits for door opening relay 40 and renders manual open switch 250 ineffective.

Switch 184 when closed by actuation of relay 180 provides a holding circuit for relay 180 by connecting the hot side of the power line to operating winding 182 of the relay, so long as treadle relay is not actuated. Actuation of treadle relay 70 breaks the holding circuit and de-energizes relay 180. Switch 184 being closed connects conductor 262 to the hot side of the power line and thus provides power to conductor 264 which energizes a close door motor energizing relay 200 which upon actuation closes a normally open single pole, single throw switch 204 to energize the motors door closing winding 22.

A presence relay 210 is controlled by the presence sensor which detects the presence of an object such as a vehicle or person in the doorway. The preferred presence detector is photocell 30, however, other presence sensors such as capacitive, inductive, ultrasonic and radar systems may be employed. Since the preferred presence sensor is a photocell, presence relay 210 will hereinafter be referred to as photorelay 210.

Photorelay 210 is controlled by a photorelay operating circuit 230. Relay 210 has an operating winding 212 which is normally energized. A single P le, single throw switch 218 is held normally open by the actuation of operating winding 212. 0ne of the contacts of switch 218 is connected to conductor 264 and the other is connected to the hot side of the power line, conductor 266. Winding 212 also controls a single pole, double throw switch 214 having a moving contact 216 which is connected to conductor 264. The normally closed contact of switch 214 connects conductor 264 to the winding 202 of close door energization relay 200. The normally open contact of switch 214 connects to the operating winding 162 of interlock relay and to the normally open switch 164.

The photorelay operating circuit employs two

vacuum tubes

232 and 234 and a photoresponsive tube as the light sensing device. Tube 232 is a pentode beam power amplifier such as a SAQS, while tube 234 is a miniature thyratron such as a 2D2 l Photorelay operating circuit 230 controls the operation of the photorelay whereby upon the light beam being interrupted the relay is de-energized and after re-establishment of the beam, the relay is re-energized after a predetermined time. The predetermined time is controlled by the discharging of capacitor 236 which is fully charged by interruption of the light beam. Switch 82 which is controlled by treadle relay 70 shorts capacitor 236 each time the treadle relay is operated in order to fully discharge capacitor 236, thereby-assuring that photorelay 210 is in its actuated condition. When capacitor 236 is discharged, the door close delay system is in its rest condition.

Several manually operated switches are provided to compliment and augment the automatic operation of the controller, Some of these switches have already been discussed, however, each will be mentioned here for completeness. Switch 240 is the power on-off switch and connects manual stop switch 254 and thus hot power bus 266 to the main source of power. This switch may be used to stop the door at any point, however, it is preferable to use the manual stop switch 254.

A manual do-not-close switch 242 connects conductor 262 to conductor 264. Opening this switch prevents a close pre-set relay from being energized and thus prevents the door from being automatically closed.

Switch 244 is a photo-override switch which when operated disables interlock relay 160 and prevents it from opening switch 166, when the photorelay would otherwise energize the interlock relay. This allows the door to be manually controlled in the event that the light source burns out so that no beam strikes the photo-cell 30.

Switch 246 is a night switch which turns off treadle switch 36 so that cars driving over the bell hose 34 will not cause the door to open, even though the control system is on.

Switch 248 is a manual door close switch which when closed energizes the close door energization relay 200. In the event that the light source is burned out, this switch must be actuated in combination with switch 244 is order to close the door.

Switch 250 is a manual door open switch which when closed energizes the door open motor energization relay to energize winding'20 to open the door.

Switch 252 is a manually operated emergecy reverse switch which may be used to energize the emergency reverse relay to cause the closing door to instantaneously reverse and open.

Switch 254 is a manually operated stop switch which stops the door in whatever position it is in when the switch is pressed.

OPERATION OF THE PREFERRED EMBODIMENT The operation of the preferred embodiment of the invention will now be explained by following, step-bystep, a complete cycle of door operation.

At the beginning of the door operation cycle every switch is in its normal position, the power switch 240 being closed to energize the control system and the night switch 246 being closed to energize the treadle switch 36.

The door operation cycle is initiated by a vehicle driving across treadle hose 34. The weight of the vehicles wheels on hose 34 actuates treadle switch 36, closing the switch and thereby forming a complete circuit from the hot power line bus 266 through treadle switch 36, night switch 246, treadle relay operating winding 72 and back to the grounded power bus 268. The current through operating winding 72 creates a magnetic field which attracts the moving

contacts

78 and 84 of the single pole, double throw switches 76 and 82. Contact 84 completes a circuit through its normally open contact thus shorting the photorelay control circuit capacitor 236, thus assuring that photorelay 210 is in its normal operated condition.

Moving contact "7% connects open signal conductor 260 to the hot power bus 266 upon making contact with its normally open contact. This completes a circuit through operating winding 1122 of re-open delay relay 120 and open limit switch 66 back to the grounded power supply bus 268. This actuates re-open delay relay 120, closing switch 124 and establishing a holding circuit for relay H24 This initiates a delay re-open timing cycle controlled by delayed switch 1102.

Close limit switch 62 is open since door 12 is fully closed, therefore no current flows through operating winding 142 of delay selection relay 14GB and delay bypass switch 1 is closed. This switch connects conductor 26% directly to the operating winding 42 of open motor energizing relay 49 to complete a circuit through the operating winding and open limit switch 60. The current which consequently flows through operating winding 42 immediately builds a magnetic field which attracts the moving contacts of single pole, single throw switches 46 and 54. Closing of switch 54 creates a holding circuit from hot power bus 266 through normally closed switch 186, switch 54, operating winding 42 and open limit switch 6%. This holding circuit will hold relay 40 energized until switch l is opened or limit switch 60 is opened by the door being fully opened. While relay 40 was being energized through switch H44 and the holding circuit through switch 54 was being established, current was flowing throughheater 108 of thermal delay Switch 1102. After the'delay time of switch 102 (a few seconds) delay switch MP2 closes, energizing the circuit formed by switch 124, thermal delay switch 102 through its terminal 164, switch 126, operating winding 42 of relay 44D and close limit switch 60. Therefore, even if switch W6 is opened prior to door 12 being fully opened so that limit switch ddopens, a holding circuit for relay 40 is maintained through the reopen delay relay 12th.

The establishmentof the above described circuits is unaffected by the length of time that treadle switch 36 isclosed, so long as it is closed for a sufficient time to actuate relay 70, since relay 7413 upon actuation remains operated long enough to actuate reopen delay relay 120 and open motor energizing relay 443.

The operation of relay 46D energizes motor E8 to open door 12. As the door opens, close limit switch 62' changes from its normally open position to aclosed condition within the first few inches of door travel. This causes current to flow through operating winding 142 of delay selection relay 141]) thus opening switch 144. This removes the energization circuit for relay 40 which by-passes reopen delay relay 1120, however, at

this point the relay holding circuit through switch 54 has been established and assures the continued actuation of relay 46 until delay switch W2 actuates to provide an alternate energization circuit.

Once treadle switch 36 is no longer actuated by the weight of the vehicle in travel lane 34, treadle relay 70 is de-energized and switches 76 and 82 return to their normal conditions. Switch 82 reconnects timing capacitor 236 in the timing circuit of the photorelay control circuit 236. The shorting of capacitor 236 by switch 82 has assured that photorelay 21s is now in its actuated condition, even if it was de-actuated previously.

When the light beam is interrupted, photosensor 30 becomes a high impedance, thus allowing a high voltage to be impressed across capacitor 236. Capacitor 236 is charged so that its upper plate is positive with respect to its lower plate. Charging current through capacitor 236 is restricted to unidirectional flow by tube 234 during the period the light beam is interrupted. The charging of capacitor 236 drives the grid of tube 232 negative beyond cutoff, thereby cutting off the operating current for photorelay 210. This deactuates the relay.

When the light beam is re-established, photosensor 30 once again becomes a low impedance for voltage which tends to retain capacitor 236 charged. The capacitor discharges through its parallel resistor, which is made variable to control the discharge time of the capacitor. Once capacitor 236 discharges to less than the cutoff voltage of tube 232, tube 232 begins conducting again, thus re-actuating relay 210.

The discharge time of capacitor 236 is preferably set to assurethat photorelay 210 cannot be de-actuated and re-actuated during the period of time it takes door 12 to open fully. The importance of this feature will be discussed hereinafter in connection with the closing of the door.

Four different situations can arise while door 12 is opening. First, no external stimuli may be impressed on the control circuitry until after the door is fully opened. in that event, motor relay 40 is de-actuated by the opening of limit switch 60 and subsequent events must be awaited to initiate the closing of the door. The closing of the door will be discussed hereinafter.

Second, another vehicle or another set of wheels on the same vehicle may cross treadle hose 34 while the door is still opening. This reactuates treadle switch 36 and treadle relay 70 which again actuates

switches

76 and 82. The actuation of switch 76 has no effect on the control circuitry since relay 120 is held actuated by its holding circuit through switch 124 and switch 144 is now open. The operation of switch 82 again shorts capacitor 236, assuring that photocontrol circuit 230 is in its rest condition. After release of treadle switch 36 and de-actuation of relay 70 the situation is one in which the door is continuing to open as above.

Third, a vehicle may pass through the doorway interrupting the light beam from light source 32 to photocell 30. This causes capacitor 236 to charge, which as discussed above cuts tube 232 off and interrupts the flow of current through the operating winding 212. This causes photorelay 210 to de-actuate so that

switches

214 and 218 change states. When switch 218 changes states, it connects the hot power line bus 266 to conductor 264 and to the moving contact 216 of switch 214. The connection of the hot power line to conductor 264 creates an actuation circuit for close preset relay 180 in which current flows through switch 218, do-notclose switch 242, operating winding 182, photooverride switch 244 and close limit switch 62 to the grounded power supply bus 268. Actuation of relay 180 attracts the moving contacts of switches 184 and 186, thus closing switch 184 and opening switch 186. The opening of switch 186 breaks the holding circuit for relay 40 which is formed through

switch

54 and 186. However, as noted above, re-open delay relay 120 forms another holding circuit for relay 40.

Closing of switch 184 connects conductor 262 to the normally closed contact of switch 76. If the treadle relay 70 is unactuated, this connects hot power supply bus 266 to conductor 262 and forms a holding circuit for close pre-set relay 180. This holding circuit will be retained until treadle relay is operated, manual stop switch 254 is actuated or close limit switch 62 opens as a result of the door closing fully.

Turning now to the effects of switch 214 changing states upon de-actuation of photorelay 210, it can be seen that an energ'ization circuit for interlock relay is formed by conductor 266, switch 218, conductor 264, switch 214, operating winding 162 of relay 160, photo-override switch 244 and close limit switch 62. Actuation of relay 160 attracts the moving contacts of switches 164 and 166, thus closing switch 164 and opening switch 166. The opening of switch 166 renders manual close switch 248 ineffective to cause the door to close. This is to prevent the door from closing while an object is obstructing the light beam. The closing of switch 164 produces no effect in the rest of the control circuitry, since relay 120 which it would actuate is being held actuated by its holding circuit through switch 124.

Even if the photobearn is re-established prior to the door becoming fully open, photorelay 210 will not be re-actuated until after the door is fully opened, since capacitor 236 has a discharge time which is greater than the length of time it takes the door to open. Therefore, the door will continue to open without further effect from the photorelay;

Fourth, after the light beam has been interrupted and re-established,'but while door 12 is still opening, trea' dle switch 36 can be re-actuated by another vehicle. This actuates switches 76 and 82. Re-actuation of switch 82 once again shorts timing capacitor 236 to return photorelay control circuit 230 to its rest condition as described above. Re-actuation of switch 76 interrupts the holding circuit for relay which is formed through switch 184. However, this has no significant effect, since relay 180 is still held operated by switch 218 of photorelay 210.

No matter which of the above sequence of events occurs, open limit switch 60 opens when the door becomes fully opened, thus interrupting the current flow through operating winding 42 of relay 40 to de-actuate the relay and de-energize mo'tor 18's open winding 20. The opening of limit switch 60 also breaks the current flowing through reopen delay relay 120, thus causing it to de-actuate.

The door close cycle will depend on which of the four difi'erent situations arose during the opening of doorv 12. The operation as a result of the first and second situations differs only in when timing-capacitor 236 will become discharged. Since this effects the timing, but not the sequence of events these two situations can be handled here without differentiating between them. Once the door has become fully open without the light beam being interrupted, the door will remain open until the light beam is interrupted and re-established. If a vehicle should actuate treadle switch 36 before the light beam has been interrupted, its only efiect is to short capacitor 236 to completely discharge it. Switch 76 causes no effect in reopen delay relay 120 since open limit switch 60 is open.

Now assume that a vehicle passes through the doorway, thus interrupting the light beam. This causes photorelay 210 to de-actuate as explained above. This deactuation of photorelay 210 produces the same effects as were described above in situation three of the door opening cycle. Thus, relay 180 is actuated to establish its holding circuit through switches 184 and 76, and interlock relay 160 is actuated to render manual close switch 248 ineffective and to close switch 164 which however, produces no effect on reopen delay relay 120 since open limit switch 60 is open. No further significant events will occur until the light beam is reestablished. Once the light beam is re-established, timing capacitor 236 begins to discharge. When capacitor 236 becomes sufficiently discharged, tube 232 conducts heavily enough to re-actuate photorelay 210. Reactuation of photorelay 210 opens switch 218 and causes switch 214 to return to its normal position. Opening switch 218 removes the circuit path from hot power bus 266 to conductor 264 which passes through switch 218. Return of switch 214 to its normal position connects conductor 264 to one end of operating winding 202 of close motor energizing relay 200. This connects the hot power line bus 266 to operating winding 202 through a path comprised of switch 76, switch 184,

do-not-close switch 242 and switch 214. This actuates relay 200 closing switch 204 to energize the motor close winding 22.

The operation of the close timing circuitry as a result of the occurrence of either the third or fourth situation during the door opening cycle is similar to that just .discussed, except that the light beam has also been interrupted and re-established prior to the door becoming completely opened and therefore, only the discharging of capacitor 236 must be awaited before photorelay 210 will re-actuate to energize motor close relay 200.

The closing of door 12 having been initiated in the manner just described, all the control circuitry is in its normal condition except close limit switch 62 is closed and close preset relay 180 and close motor energizing relay 200 are both actuated so that switches 184 and 204 are closed and switch 186 is open and finally current flows through actuating winding 142 of delay selection relay 140 so that switch 144 is open. As can be seen from the diagram, the only holding circuit which holds close preset relay 180 actuated is composed of switch 76, switch 184, operating winding 182, photooverride switch 244 and close limit switch 62. The holding circuit for motor close relay 200 is comprised of switch 76, switch 184, conductor 262, do-not-close switch 242, conductor 264, switch 214, operating winding 202 and close limit switch 62.

Four different situations can arise while the door 12 is closing. First, no control events may occur while the door is closing. In this event, close limit switch 62 opens when the door becomes fully closed thereby breaking the holding circuits for

relays

180 and 200 and de-actuating them to de-energize motor close.

winding 22.

Second, a vehicle may drive over treadle'hose 34 While the door is closing. This actuates treadle switch 36 which energizes treadle relay 70 to attract moving contact 78 of switch 76. Movement of moving contact 78 breaks the holding circuit for

relays

180 and 200, thus de-energizing motor close winding 22 to stop the doors motion. When moving contact 78 makes contact with its normally open contact, it connects the hot power bus 266 to the open signal conductor 260. This provides an actuation circuit for reopen relay 120 which is comprised of switch 76, operating winding 122 and open limit switch 60. Relay 120 is thus actuated attracting the moving contacts of switches 124 and 126. Switch 124 when closed forms a holding circuit to maintain relay energized. Switch 126 connects terminal 104 of delay switch 102 to the high side of oper-' ating winding 42 of open motor energizing relay 40. It is noted at this point that since switch 144 is open, relay 40 is not immediately energized as was the case when the door was fully closed. The connection of the hot power line to conductor 260 causes current to flow through heater 1080f delay switch 102. This heater heats the bimetallic contact 110 which at the end of the prescribed delay period closes an energizing circuit for relay 40. This energizing circuit is composed of switch 124, terminal 106, contact 110, terminal 104, switch 126, operating winding 42 and open limit switch 60. The completion of this energizing circuit actuates the relay to energize the open motor winding 20. The door is therefore caused to reopen. For all relevant purposes, once relay 40 has been actuated the door is now in a door open cycle as was discussed above. Thus, a door reversal operation has taken place in which the closing door was stopped by d'c-actuati'on of close motor relay 200 and de-energization of close windings 22 of the motor and then after a predetermined delay of a few seconds the door was reopened. Thus the ob-. ject of reversing the doors motion without jerking the v door' has been accomplished.

The third situation which may arise is that while the door is closing an object may obstruct'the light beam from light source 32 tophotocell 30. In response to such an obstruction of the light beam, photorelay control circuit 230 de-actuates photorelay 210 causing

switches

214 and 218 to switch. Switching of switch 214 opens the energization circuit for close motor ene'rgizing relay 200 to open switch 204, and de-energize motor close winding 22, thus stopping the door. Switch 218 connects the hot side of the power supply to conductor 264 and to the moving contact 216' of switch 214. Moving contact 216 of switch 214 which is now in contact with the normally open contact of switch 214 completes an energization circuit for interlock relay which actuates that relay. This energization circuit is composed of switch 218, conductor 264, switch 214, operating winding 162, photo-override switch 244, and close limit switch 62. Actuation of in terlock relay 160 closes switch 164 which connects the hot side of the power supply to open signal conductor 260. Thereafter, the operation of the reopen delay relay and delay switch is the same asit was in the second' situation above in which it was the treadle relay switch which initiated the reversal of the door. It is to be noted, however, that close preset relay is still actuated, since switch 76 has not been switched. However, as discussed in connection with the opening cycle of the door the photorelay control circuit 230 will not re-actuate the photorelay 210 until after the door is fully opened. Thus, close motor relay 200 will not be re-actuated until after the door is fully opened.

The fourth situation which may occur while the door is closing is that the safety edge 38 on the bottom of breaks the holding circuit for the close pre-set relay 180 and close motor relay 200 while switch 82 discharges capacitor 236. This stops the doors downward movement. Simultaneously with the actuation of treadle relay 70, the closure of switch 136 completes an energization circuit for open motor relay 40. This circuit extends from the hot side of the power line through switch 136, operating winding 42 and open limit switch 60. This immediately energizes the motor in the open direction. Thus, the closure of

switches

134 and 136 produce an instantaneous reversal of the direction of rotation of motor 18, thereby stopping the door in the minimum distance and causing it to reopen. It is noted that when relay 40 actuates, it completes a holding circuit comprised of open limit switch 60, switch 54 and switch 186 which is now closed since close pre-set relay 180 has been de-actuated by treadle relay 70.

In the second and fourth situations which may arise while the door is closing, the light beam must be interrupted and re-established before the door can bereclosed, since deactuation of photorelay 210 is necessary in order to actuate close pre-set relay 180. In the third situation, that in which the door reversal was initiated by interruption of the light beam, the light beam only needs to be re-established and capacitor 236 discharged to cause the door to close again. Thus, once the door has fully reopened the situation is similar to that where the door started to open from the fully closed position.

Once the door has fully closed as in the first situation for the closing door, the door is ready to be reopened in the same fashion as occurred initially. That is the door will open immediately upon actuation of the treadle switch 36, since switch 144 will be closed (close limit switch 62 being open).

On additional situation needs to be considered for a full understanding of the operation of the preferred controller. That is a situation where the door is fully closed and someone inside the garage obstructs the light beam. This will cause photorelay 210 to deactuate, thus, connecting the hot side of the power line to conductor 264 through switch 218 to moving contact 216 of switch 214 and thus, to the operatingwinding 162 of interlock relay 160. Since door 12 is fully closed, close limit switch 62 is open and no energizing current flows through interlock operating winding 162. Therefore, switch 164 does not close and door 12 remains closed. Thus, when the door is fully closed traffic attempting to pass through the doorway in the wrong direction does not initiate a door open cycle.

While a thermal delay switch is preferred as delay timer 102, other types of timers may be employed. 1f the timer used deteriorates with use, delay by-pass switch 144 may be changed from a single pole single throw (SPST) switch to a single pole double throw switch (SPDT). The SPDT switch is wired so that reopen delay relay 120 is actuated only when the door is partially open. This saves delay timer 102 from actuation when the door opens from the fully closed position.

While the invention has been described in terms of the operation of the preferred embodiment, it will be understood by those skilled in the art that variations may be made in this embodiment without departing 6 from the spirit and scope of the invention.

I claim:

1. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an instantaneously electrically reversible motor, said door control system comprising:

a treadle switch which is operated by a bell hose in response to a vehicle driving over the hose in the travel lane;

treadle relay means having an actuation circuit which is completed by operation of the treadle switch;

door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the door;

reopen delay relay means having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened;

a delay switch connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay switch completing an actuation circuit for the open motor relay upon expiration of its delay period;

a relay by-pass switch connected to the treadle relay and the open motor relay for immediately completing an energizationcircuit for the open motor relay when the delay by-pass switch is closed and the treadle relay operates, said delay by-pass switch being operated by a delay selection relay, said switch being closed when the door is fully closed and open at all other times;

a light source means located on the first side of the doorway, said light source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway;

a photocell on the first side of the doorway and across the travel lane from the light source and positioned to receive the light beam;

a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photorelay control circuit being in a rest condition and the photorelay is actuated and the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re'establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period;

a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay,

and having a holding circuit which is broken by operation of the treadle relay;

door close motor energizing relay means having an actuation circuit which ,is completed by re-action of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by deactuation of the photorelay;

a safety edge on the leading edge of the door for sensing the presence of an obstruction in the path of the closing door, said safety edge operating an emergency reverse switch upon striking an object;

emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door; an interlock relay having an actuation circuit which is completed by de-actuation of the photo-relay, except when the door is completely closed, said interlock relay operating an interlock switch which when closed completes an actuation circuit for the reopen delay relay, except when the door is fully open, whereby interruption of the light beam while the door is closing breaks the operating circuit for the close motor relay and operates the reopen delay relay to energize the delay switch to energize the open motor relay after a predetermined delay time whereby the closing door is stopped for a moment and then reopened. 2. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an electrically reversible motor, said door control system comprising:

a treadle switch which is operated by a sensor in response to a vehicle driving in the travel lane; treadle relay means having an actuation circuit which is completed by operation of the treadle switch; door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the door;

delay means connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period;

a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photo-relay control circuit being in a rest condition when the photorelay is actuated and the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photore lay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period; de-actuation of the photorelay completing an actuation circuit for the reopen delay relay, except when the door is fully open,

a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay, and having a holding circuit which is broken by operation of the treadle relay;

door close motor energizing relay means having an actuation circuit which is completed by reactuation of the photorelay while'the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photo-relay. I

3. The apparatus of claim 2 wherein the motor is instantaneously electrical reversible and the motor control circuit further comprises:

an emergency reverse sensor on the door for sensing the presence of an obstruction in the path of the closing door, said sensor operating an emergency reverse switch upon sensing an object;

emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor 'relay to instantenously reverse the motor and reopen the door. 4. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing, through the doorway, said door being driven by an electrically reversible motor, said door control system comprising:

a treadle switch which is operated by a sensor in response to a vehicle driving in the travel lane;

door open motor energizing relay means having a relay operated switch which completes and energization circuit for energizing the motor to open the door; I

delay means connected to the reopen delay relay to be energized by the operation of thereopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period;

a light source means located on the first side of the doorway, said light source producing a beam of light extending across the travelv lane to be interrupted by an object passing through the doorway;

a photocell on the first side of the doorway and across the travel lane from the light source. and positioned to receive the light beam;

a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photorelay control circuit being in a rest condition and the photorelay being actuated when the light beam ispresent at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period;

door close motor energizing relay means having an actuation circuit which is completed by reactuation of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photorelay;

an interlock relay having an actuation circuit which is completed by de-actuation of the photo-relay, except when the door is completely closed; said interlock relay operating an interlock switch which when closed completes an actuation circuit for the reopen delay relay, except when the door is fully open; whereby interruption of the light beam while the door is closing breaks the operating circuit for the close motor relay and operates the reopen delay relay to energize the delay switch to energize the open motor relay after a predetermined delay time whereby the closing door is stopped for a moment and then reopened.

5. The apparatus of claim 4 wherein the motor is instantaneously reversible and the door control system further comprises:

an emergency reverse switch;

emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close-preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door.

6. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side and the other side being an exit side, and having a travel lane passing through the doorway, said door control system comprising:

an instantaneously reversible electric motor for opening and closing the door;

a treadle switch for providing an electrical open door command signal, said switch being operated by a car driving in the travel lane;

a motor energizing door opening relay operated by the open door command signal to energize the motor to open the door, said relay having a holding circuit for retaining the relay energized after the door open command signal has terminated,

an open limit switchfor interrupting the relay holding and energizing circuits when the door is fully open, thereby de-energizing the motor and preventing the motor from being energized in the open direction until the door is partially closed;

a light source located on the first side of the doorway,

said light source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway;

delay means for initiating automatic closing of the door, said delay means having a rest condition and while in said rest condition being responsive to interruption and reestablishment of the light beam to initiate a delay period, said delay means producing a close door command signal at the end of the delay' period,

reset means responsive to actuation of the treadle, said reset means resetting the delay means to its rest condition in response to a door open command signal which is received while the delay means is in the delay period;

a door close relay operated by the door close command signal for energizing the motor to close the door;

a close limit switch responsive to the door closing completely for interrupting the door-close relays energization circuit;

door reversing means, said door reversing means being responsive, while the door is closing, to ac'tuation of a treadle or interruption of the light beam to terminate the close door command signal and de-energize the door close relay and the motor, said reversing means producing an open door. command signal a predetermined time later to energize the door open relay and the motor to reopen the door, said reversing means being responsive to an emergency reverse command signal to instantaneously reverse the energization of the-motor by terminating the close door command signal and producing a door open command signal to immediately reverse the direction of door travel to reopen the door.

7. An automatic door control system for controlling a door which controls passage through a doorway, said door being powered by a reversible electric motor, said control system comprising:

treadle switch means operated by a sensor inzresponse to an object approaching the door;

treadle relay means actuated by the treadle switch means; the door;

door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open theldoor;

a reopen delay relay having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened;

a delay means connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period;

presence sensor means responsive to the presence of an object in the doorway, said presence sensor assuming a first condition when no object. is in the doorway and a second condition when an object is in the doorway;

presence relay means assuming a first condition when the presence sensor is in its first condition and assuming a second condition when the presence sensor is in its second condition;

close preset relay means having an actuation circuit which is completed by the presence relay assuming its second condition, and having a holding circuit an emergency reverse switch;

which is broken by operation of the treadle relay; emergency reverse relay means'having an actuating door close motor energizing relay means having an 7 circuit which is completed by operation of the actuation circuit which is completed by the presemergency reverse'switch, said emergency reverse ence relay assuming its first condition while the relay actuating the the treadle relay to break the close preset relay is actuated, said actuation circuit holding circuits of the close-preset relay and the being interrupted by tie-actuation of the close preclose motor relay to de-energize the motor from its set relay means and by the presence relay assuming door close condition, said emergency reverse relay its second condition. also completing an actuation circuit for the open 8. The apparatus of claim 7 wherein the motor is in- 10 motor relay to instantaneously reverse the motor stantaneously reversible and the door control system and reopen the door.

further comprises: a:

Claims

1. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an instantaneously electrically reversible motor, said door control system comprising: a treadle switch which is operated by a bell hose in response to a vehicle driving over the hose in the travel lane; treadle relay means having an actuation circuit which is completed by operation of the treadle switch; door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the door; reopen delay relay means having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened; a delay switch connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay switch completing an actuation circuit for the open motor relay upon expiration of its delay period; a relay by-pass switch connected to the treadle relay and the open motor relay for immediately completing an energization circuit for the open motor relay when the delay by-pass switch is closed and the treadle relay operates, said delay by-pass switch being operated by a delay selection relay, said switch being closed when the door is fully closed and open at all other times; a light source means located on the first side of the doorway, said liGht source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway; a photocell on the first side of the doorway and across the travel lane from the light source and positioned to receive the light beam; a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photorelay control circuit being in a rest condition and the photorelay is actuated and the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period; a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay, and having a holding circuit which is broken by operation of the treadle relay; door close motor energizing relay means having an actuation circuit which is completed by re-action of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photorelay; a safety edge on the leading edge of the door for sensing the presence of an obstruction in the path of the closing door, said safety edge operating an emergency reverse switch upon striking an object; emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door; an interlock relay having an actuation circuit which is completed by de-actuation of the photo-relay, except when the door is completely closed, said interlock relay operating an interlock switch which when closed completes an actuation circuit for the reopen delay relay, except when the door is fully open, whereby interruption of the light beam while the door is closing breaks the operating circuit for the close motor relay and operates the reopen delay relay to energize the delay switch to energize the open motor relay after a predetermined delay time whereby the closing door is stopped for a moment and then reopened.

2. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an electrically reversible motor, said door control system comprising: a treadle switch which is operated by a sensor in response to a vehicle driving in the travel lane; treadle relay means having an actuation circuit which is completed by operation of the treadle switch; door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the door; reopen delay relay means having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened; delay means connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period; a light source means located on the first side of the doorway, said light source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway; a photocell on the firSt side of the doorway and across the travel lane from the light source and positioned to receive the light beam; a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photo-relay control circuit being in a rest condition when the photorelay is actuated and the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period; de-actuation of the photorelay completing an actuation circuit for the reopen delay relay, except when the door is fully open, a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay, and having a holding circuit which is broken by operation of the treadle relay; door close motor energizing relay means having an actuation circuit which is completed by re-actuation of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photo-relay.

3. The apparatus of claim 2 wherein the motor is instantaneously electrical reversible and the motor control circuit further comprises: an emergency reverse sensor on the door for sensing the presence of an obstruction in the path of the closing door, said sensor operating an emergency reverse switch upon sensing an object; emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantenously reverse the motor and reopen the door.

4. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an electrically reversible motor, said door control system comprising: a treadle switch which is operated by a sensor in response to a vehicle driving in the travel lane; treadle relay means having an actuation circuit which is completed by operation of the treadle switch; door open motor energizing relay means having a relay operated switch which completes and energization circuit for energizing the motor to open the door; reopen delay relay means having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened; delay means connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period; a light source means located on the first side of the doorway, said light source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway; a photocell on the first side of the doorway and across the travel lane from the light source and positioned to receive the light beam; a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photorelay control circuit being in a rest condition and the photorelay being actuated when the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device Which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period; a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay, and having a holding circuit which is broken by operation of the treadle relay; door close motor energizing relay means having an actuation circuit which is completed by re-actuation of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photorelay; an interlock relay having an actuation circuit which is completed by de-actuation of the photo-relay, except when the door is completely closed; said interlock relay operating an interlock switch which when closed completes an actuation circuit for the reopen delay relay, except when the door is fully open; whereby interruption of the light beam while the door is closing breaks the operating circuit for the close motor relay and operates the reopen delay relay to energize the delay switch to energize the open motor relay after a predetermined delay time whereby the closing door is stopped for a moment and then reopened.

5. The apparatus of claim 4 wherein the motor is instantaneously reversible and the door control system further comprises: an emergency reverse switch; emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close-preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door.

6. An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side and the other side being an exit side, and having a travel lane passing through the doorway, said door control system comprising: an instantaneously reversible electric motor for opening and closing the door; a treadle switch for providing an electrical open door command signal, said switch being operated by a car driving in the travel lane; a motor energizing door opening relay operated by the open door command signal to energize the motor to open the door, said relay having a holding circuit for retaining the relay energized after the door open command signal has terminated, an open limit switch for interrupting the relay holding and energizing circuits when the door is fully open, thereby de-energizing the motor and preventing the motor from being energized in the open direction until the door is partially closed; a light source located on the first side of the doorway, said light source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway; a photocell on the first side of the doorway and across the travel lane from the light source and positioned to receive the light beam; delay means for initiating automatic closing of the door, said delay means having a rest condition and while in said rest condition being responsive to interruption and reestablishment of the light beam to initiate a delay period, said delay means producing a close door command signal at the end of the delay period, reset means responsive to actuation of the treadle, said reset means resetting the delay means to its rest condition in response to a door open command signal which is received while the delay means is in the delay period; a door close relay operated by the door close command signal for energizing the motor to close the door; a close limit switch Responsive to the door closing completely for interrupting the door-close relays'' energization circuit; door reversing means, said door reversing means being responsive, while the door is closing, to actuation of a treadle or interruption of the light beam to terminate the close door command signal and de-energize the door close relay and the motor, said reversing means producing an open door command signal a predetermined time later to energize the door open relay and the motor to reopen the door, said reversing means being responsive to an emergency reverse command signal to instantaneously reverse the energization of the motor by terminating the close door command signal and producing a door open command signal to immediately reverse the direction of door travel to reopen the door.

7. An automatic door control system for controlling a door which controls passage through a doorway, said door being powered by a reversible electric motor, said control system comprising: treadle switch means operated by a sensor in response to an object approaching the door; treadle relay means actuated by the treadle switch means; the door; door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the1door; a reopen delay relay having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened; a delay means connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay means completing an actuation circuit for the open motor relay upon expiration of its delay period; presence sensor means responsive to the presence of an object in the doorway, said presence sensor assuming a first condition when no object is in the doorway and a second condition when an object is in the doorway; presence relay means assuming a first condition when the presence sensor is in its first condition and assuming a second condition when the presence sensor is in its second condition; close preset relay means having an actuation circuit which is completed by the presence relay assuming its second condition, and having a holding circuit which is broken by operation of the treadle relay; door close motor energizing relay means having an actuation circuit which is completed by the presence relay assuming its first condition while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay means and by the presence relay assuming its second condition.

8. The apparatus of claim 7 wherein the motor is instantaneously reversible and the door control system further comprises: an emergency reverse switch; emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the the treadle relay to break the holding circuits of the close-preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door.