Energy saving motor-driven locking subsystem

• US 7,006,799 B2
• Filed: 09/30/2002
• Issued: 02/28/2006
• Est. Priority Date: 09/30/2001
• Status: Expired due to Term

• Current Assignee: Harrow Products LLC (Allegion PLC)
• Original Assignee: Harrow Products LLC (Allegion PLC)
• Inventors: Wiemeyer, James F., Liu, Zhen
• Primary Examiner(s): Tran, Pablo N.
• Application Number:
  US10/262,207
• Publication Number:
  US 20030100266A1
• Time in Patent Office: 1,247 Days
• Field of Search: 455/572, 455/67.11, 455/414.1, 455/41.1, 455/41.2, 455/66.1, 455/67.13, 455/74, 455/556.1, 455/554.2, 455/574, 455/90.3, 340/825.54, 340/825.34, 340/10.1, 340/10.31, 340/10.42, 340/10.51, 340/10.52, 340/330, 340/286.11, 340/49.6, 318/480, 318/266, 318/282, 318/286, 235/491, 235/492
• US Class Current: 455/67.11
• CPC Class Codes: G07C 2009/00634 Power supply for the lock
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/08 With time considerations, e.g. temporary activation, valid time window or time limitations
• CPC Class Codes: G07C 2209/62 Comprising means for indicating the status of 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
• CPC Class Codes: G07C 9/00571 operated by interacting with a central unit
• CPC Class Codes: G07C 9/27 with central registration
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In an access control system, a method and system for conserving battery life comprising an electronic control processor in a motor-driven locking subsystem for measuring samples of back electromotive force from a DC motor within the motor-driven locking subsystem. The samples of the back electromotive force are summed by the electronic control processor to form a comparison parameter value. The comparison parameter value is compared to a pre-determined threshold value to form a decision parameter. An action is taken by the electronic control processor in the motor-driven locking subsystem based on the decision parameter. This action comprises one of commanding the battery source in the motor-driven locking subsystem to increase the voltage level to the motor, generating a fail signal, or detecting and indicating a lock or unlock condition.

Claims

1. In an RF access control system, a method for reducing the power used to lock or unlock an access point, said access point including a locking shaft, a motor driving said locking shaft and a motor armature, and an electronic control processor controlling said motor;

said method including the steps of;

providing power to a motor during an initial drive time so that a locking shaft is set in motion;

ceasing to supply power to said motor;

periodically measuring the back EMF from said motor during a time interval when the motor armature has a substantially zero current value and summing the measurements of said back EMF to form a summed back EMF measurement;

comparing said summed back EMF measurement to a predetermined threshold;

again providing power to said motor if said summed back EMF measurement is less than said predetermined threshold.

2. The method of claim 1 wherein said back EMF is measured every 10 ms.

3. The method of claim 1 wherein said again providing power step includes applying power for around 10 ms.

4. The method of claim 1 wherein said again providing power step includes only providing power for a predetermined plurality of times.

5. The method of claim 4 wherein said again providing power step includes only providing power over a predetermined time period.

6. The method of claim 4 further including the step of indicating a stall of said motor when said predetermined number of times is reached and said threshold has not been met.

7. The method of claim 1 wherein said again providing power step includes providing a power at a different power level than said initial power application.

8. The method of claim 1 further including the step of measuring the back EMF from said motor before ceasing to supply power to said motor to obtain a pre-shutoff back EMF measurement.

9. The method of claim 8 further including the steps of:

summing the pre-shutoff back EMF measurements to form a summed pre-shutoff back EMF measurement; and

comparing said summed pre-shutoff back EMF measurement to a predetermined shutoff threshold.

10. The method of claim 9 wherein said ceasing to supply power step is triggered when said summed pre-shutoff back EMF measurement exceeds said predetermined shutoff threshold.

11. An RF access control system including:

a locking shaft;

a motor driving said locking shaft so that said locking shaft is set in motion and then ceasing to drive said locking shaft; and

an electronic control processor periodically measuring the back EMF from said motor when said motor is exhibiting a substantially zero motor current, summing the measurements of said back EMF to form a summed back EMF measurement, comparing said summed back EMF measurement to a predetermined threshold, and re-activating said motor if said summed back EMF measurement is less than said predetermined threshold.

12. The access control system of claim 11 wherein said back EMF is measured every 10 ms.

13. The access control system of claim 11 wherein said motor is reactivated for around 10 ms.

14. The access control system of claim 11 wherein said electronic control processor reactivates said motor for a predetermined plurality of times.

15. The access control system of claim 14 wherein said electronic control processor only reactivates said motor over a predetermined time period.

16. The access control system of claim 14 wherein said electronic control processor indicates a stall of said motor when said predetermined plurality of times is reached and said threshold has not been met.

17. The access control system of claim 11 wherein said motor is reactivated as a different power level that the initial power application.

18. The access control system of claim 11 wherein said electronic control processor measuring the back EMF from said motor before ceasing to supply power to said motor to obtain a pre-shutoff back EMF measurement.

19. The access control system of claim 18 wherein said electronic control processor sums the pre-shutoff back EMF measurements to form a summed pre-shutoff back EMF measurement and compares said summed pre-shutoff back EMF measurement to a predetermined shutoff threshold.

20. The access control system of claim 19 wherein said electronic control processor ceases to provide power to said motor when said summed pre-shutoff back EMF measurement exceeds said predetermined shutoff threshold.