Abstract: This invention relates to closure retention apparatus for automatic doors, and more particularly to an electrical circuit for providing a reduced amount of electrical power to the motor which controls the opening and closing of the door. The circuitry includes first circuit means for applying a first level of power temporarily to said motor for operating the door from open toward closed position, and a second circuit for applying a second, reduced level of power continuously to the application of the first level power thereto for a preselected period of time for operating said door toward closed position also.

Abstract: This invention relates to apparatus for holding swing or slide type doors open for a controlled period of time and includes in combination a door movable between a closed first position and a fully open second position. A holding device is mounted on a stationary support in such position as to be engaged by the door when moved to its second position, this device including an electromagnet and an actuating switch so disposed as to be engaged by the door when moved to its second position. Circuitry is provided between the switch and the magnet such that upon engagement of the door with the switch, the electromagnet is energized providing a magnetic force holding the door thereagainst. The circuitry further includes time delay means for deenergizing the electromagnet and for releasing the door after a predetermined period of time.

Abstract: A timing apparatus for holding a door open for a controlled period of time before releasing it for closure. The timing apparatus includes a switch operable to produce a switching signal. A first energizing control is coupled to the switch and is responsive to the switching signal for producing a first signal. An electromagnetic device is coupled to the first energizing control and is energizable in response to the first signal. A first timing circuit is coupled to the first energizing control and is responsive to the first signal to generate a first timing signal of predetermined duration and corresponding to the switching signal. The first energizing control is further responsive to the first timing signal thereby to remain in the state of providing the first signal for such predetermined duration. A second timing circuit is coupled to the first timing circuit and is responsive to the termination of the first timing signal to produce a second timing signal of second predetermined duration.

Abstract: Motor overload current is sensed and coupled to the input of an operational amplifier, causing the amplifier output to invert and charge a plurality of parallel connected capacitors. When the overload condition is present for a predetermined time, the capacitors are sufficiently charged to change the output state of a second operational amplifier. A diode is coupled between the output and the input of the second amplifier and is poled to latch the second amplifier into its inverted state when the capacitors have reached the predetermined charge. A luminous source, such as a light emitting diode, is coupled to the output of the second amplifier and becomes non-luminous in the inverted state of the second amplifier. The diode is photo-coupled to a photo conductive circuit for disabling the power coupling to the motor circuit when the diode is non-luminous.

Abstract: The control includes approach and safety mat switches to which are applied alternating current voltage. Each of the switches are coupled to respective high gain binary output, solid-state amplifiers which change state upon alternation of two different input voltages being compared. Upon closure of the approach mat switch, the corresponding binary amplifier is caused to change state which in turn changes the state and output signal of a third like amplifier. This output signal causes the energization of an electric motor which opens the door. Opening of the approach mat switch followed by closing of the safety mat switch, the corresponding amplifier changes state and holds the third amplifier in its state which causes energization of said motor, thereby holding the door open. A time delay circuit is connected to the third amplifier for delaying the change of state of the third amplifier after the approach and safety mat switches are opened.