REDUCED POWER CONSUMPTION ELECTROMAGNETIC LOCK

• US 20170226784A1
• Filed: 04/13/2016
• Published: 08/10/2017
• Est. Priority Date: 02/09/2016
• Status: Active Grant

• Current Assignee: Hanchett Entry Systems Incorporated (Assa Abloy AB)
• Original Assignee: Hanchett Entry Systems Incorporated (Assa Abloy AB)
• Inventors: Davis, Brett L., Shaffer, Randall
• Granted Patent: US 11,203,890 B2
• Time in Patent Office: Days
• CPC Class Codes: E05B 2047/0068 Door closed
• CPC Class Codes: E05B 47/00 Operating or controlling locks or other fastening devices by electric or magnetic means electric permutation locks E05B49/00
• CPC Class Codes: E05C 19/166 electromagnetic
• CPC Class Codes: G07C 2009/00634 Power supply for the lock
• CPC Class Codes: G07C 9/00174 Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys mechanical locks with electric permutation E05B49/00; arrangements for sensing or reading record carriers G06K7/00; electronic switching H03K17/00

Abstract

An energizable electromagnet of a door locking system is affixed to the door or the door frame for electromagnetically attracting an armature affixed to the other. A power control circuit is configured to selectively energize the electromagnet using a pulse-width modulated current cycle wherein two levels of magnetic force may be selectively applied to the system. A door position sensor is configured to provide a first communication signal to the power control circuit when the door is in a closed position. A second communication signal is provided when the door is not in the closed position. The electromagnet is energized at the lower level of magnetic force when the power control circuit receives the first communication signal and at the higher level of magnetic force only when an unauthorized attempt to open the door is initiated.

Claims

1. An electromagnetic door locking system configured to cooperate with a door movable in a door frame, said door movable from a closed position to a non-closed position, the system comprising:

a) an energizable electromagnet configured to be affixed to one of said door or said door frame for electromagnetically attracting an armature, said armature affixed to the other of said door or said door frame, wherein when said door is in said closed position and said electromagnet is energized, said armature is attracted to said electromagnet thereby placing said door in a locked mode;

b) a power control circuit configured to selectively energize said electromagnet; and

c) a first sensor configured to sense a first door position when said door is in said closed position and a second door position when said door is not in said closed position;

wherein said electromagnet is energized by said power control circuit when said first sensor senses said first door position.

2. The electromagnetic door locking system of claim 1 wherein a second sensor separate from said first sensor senses said second door position.

3. The electromagnetic door locking system of claim 1 and further comprising:

d) an authentication module connected to said power control circuit, said authentication module configured to receive access credentials and send an authentication signal to said electromagnet, wherein said electromagnet is de-energized upon receipt of said authentication signal for a first predetermined period of time.

4. The electromagnetic door locking system of claim 3 wherein, if said first sensor does not sense said first door position after first sensing said second door position, said electromagnet remains de-energized irrespective of said first predetermined period of time.

5. The electromagnetic door locking system of claim 4 wherein said electromagnet remains de-energized until said first sensor senses again said first door position.

6. The electromagnetic door locking system of claim 3 wherein said electromagnet is energized if said first sensor senses said first door position after sensing said second door position, irrespective of said first predetermined period of time.

7. The electromagnetic door locking system of claim 1 wherein said first sensor is selected from one or more of the following:

an accelerometer, a capacitive sensor, a voltage sensor, a current sensor, an image sensor, a photo sensor, a pressure sensor, a micro switch, a passive infrared sensor, a radio frequency (RF) sensor and a reed switch.

8. The electromagnetic door locking system of claim 1 wherein said first sensor is configured to sense a change in magnetic bond between said electromagnet and said armature.

9. The electromagnetic door locking system of claim 3 wherein said first predetermined period of time is selectable.

10. The electromagnetic door locking system of claim 3 wherein said authentication module is one or more of a keypad, swipe card reader, key fob reader or biometric sensor.

11. An electromagnetic door locking system configured to cooperate with a door movable in a door frame, said door movable from a closed position to a non-closed position, the system comprising:

a) an energizable electromagnet configured to be affixed to one of said door or said door frame for electromagnetically attracting an armature, said armature affixed to the other of said door or said door frame, wherein when said door is in said closed position and said electromagnet is energized, said armature is attracted to said electromagnet thereby placing said door in a locked mode;

b) a power control circuit connectable to a power source, wherein said power control circuit includes a controller configured to provide power to energize said electromagnet; and

c) a transistor selectively switchable between ON and OFF states wherein said controller is configured to provide a pulse-width modulated signal to said transistor;

wherein said electromagnet is energized with a voltage having a first current level based upon said pulse-width modulated signal received from said controller to hold said door in said locked mode.

12. The electromagnetic door lock system of claim 11 wherein said power control circuit further comprises:

e) windings associated with said electromagnet and configured to receive said power from said controller through said transistor whereby, when said transistor in said OFF state, inductive current from said windings continues to flow through said windings to provide power to said electromagnet.

13. The electromagnetic door system of claim 12 wherein said power control circuit further comprises a current-sense circuit configured to read a current flowing through said windings and to send a feedback voltage signal to said controller, wherein said controller generates said pulse-width modulated signal based upon said feedback voltage signal.

14. The electromagnetic door system of claim 11 wherein said transistor is a MOSFET transistor.

15. The electromagnetic door system of claim 11 wherein said electromagnet is energized with a second voltage having a second current level based upon a second pulse-width modulated signal received from said controller.

16. A power control circuit connectable to a power source and configured for providing power to an electromagnetic device, said power control circuit comprising:

a) a controller configured to provide said power to said electromagnetic device;

b) a transistor selectively switchable between ON and OFF states, wherein said transistor is configured to receive a pulse-width modulated signal from said controller; and

c) windings associated with said electromagnetic device and configured to receive said power from said controller through said transistor having a first current level based upon said pulse-width modulated signal received from said controller, wherein, when said transistor in said OFF state, inductive current from said windings continues to flow through said windings to provide power to said electromagnetic device.

17. The power control circuit of claim 16 further comprising a current-sense circuit configured to read a current flowing through said windings and to send a feedback voltage signal to said controller, and wherein said controller generates said pulse-width modulated signal based upon said feedback voltage signal.

18. The power control circuit of claim 16 wherein said transistor is a MOSFET transistor.

19. The power control circuit of claim 16 wherein said electromagnetic device includes an electromagnet and an armature.

20. The power control circuit of claim 19 wherein said electromagnet is mounted on one of a door or a door frame and said armature is mounted on the other of said door or said door frame.

21. An electromagnetic door locking system configured to cooperate with a door movable in a door frame, said door movable from a closed position to a non-closed position, the system comprising:

a) an energizable electromagnet configured to be affixed to one of said door or said door frame for electromagnetically attracting an armature, said armature affixed to the other of said door or said door frame, wherein when said door is in said closed position and said electromagnet is energized, said armature is attracted to said electromagnet thereby placing said door in a locked mode;

b) a first sensor configured to sense a first door position when said door is in said closed position and to sense a second door position when said door is not in said closed position; and

c) a power control circuit in communication with said first sensor and configured to selectively energize said electromagnet, wherein said electromagnet is de-energized by said power control circuit when said first sensor senses said second door position.

22. The electromagnetic door locking system in accordance with claim 21 further comprising a second sensor configured to sense said first door position when the door is in said closed position and to sense said second door position when the door is not in said closed position, wherein said power control circuit is in communication with said second sensor, and wherein said electromagnet is energized by said power control circuit when either said first sensor or said second sensor, or both said first sensor and said second sensor senses said first door position.

23. The electromagnetic door locking system in accordance with claim 22 wherein said power control circuit is configured to trigger an alarm, and wherein said alarm is triggered by said power control circuit when one of said first sensor or said second sensor senses said first door position and the other of said first sensor or said second sensor does not sense said first door position.

24. The electromagnetic door locking system in accordance with claim 23 wherein said alarm comprises an audible signal, a visual signal or a visual notice.

25. The electromagnetic door locking system in accordance with claim 21 wherein said first sensor comprises a photo sensor, a pressure sensor, a micro switch, a passive infrared sensor, a radio frequency sensor, a reed switch, or a magnetic bond sensor.

26. The electromagnetic door locking system in accordance with claim 22 wherein said first sensor or said second sensor comprises a photo sensor, a pressure sensor, a micro switch, a passive infrared sensor, s radio frequency sensor, a reed switch, or a magnetic bond sensor.

27. A method of operating an electromagnetic door locking system configured to cooperate with a door movable in a door frame between a closed position and an open position, wherein said electromagnetic door locking system comprises an energizable electromagnet, a first sensor configured to sense a first door position when said door is in said closed position and to sense a second door position when said door is not in said closed position, a second sensor configured to sense said first door position and to sense said second door position, a power control circuit in communication with said first sensor and said second sensor and configured to selectively energize said electromagnet when said first door position is sensed and to de-energize said electromagnet when said second door position is sensed, wherein said power control circuit is further configured to trigger an alarm, said method comprising the steps of:

a) triggering said alarm by said power control circuit when one of said first sensor or said second sensor senses said first door position and the other of said first sensor or said second sensor does not sense said first door position; and

b) energizing said electromagnet when either one of said first sensor or said second sensor senses said first door position.