Power controller for a door lock and method of conserving power

Abstract

A power control system for use with an electric lock mechanism having an actuator comprises a power supply to output an output voltage to the actuator. A credential device signals the power supply to output the voltage upon receiving an authorized code. A microcontroller controls the power supply, the credential device, and the actuator and may operate in an Access Mode or a Dog Mode. When in Access Mode, the actuator is unpowered and the credential device is powered until an authorized code is received and the power supply powers the actuator. The Dog Mode has an awake mode where the actuator is powered and the credential device is unpowered after the actuator remains in the powered state for a length of time. A sleep mode has the actuator unpowered and the credential device powered until an authorized code is received and the power supply powers the actuator.

Claims

1. A power control system for use with an electric lock mechanism having an electric actuator, said power control system comprising: a) a power supply configured to receive power from a voltage source and to selectively provide an output voltage to said actuator; b) a credential device configured to detect a credential, and wherein, upon authentication of said credential, a signal is provided to said power supply to provide said output voltage to said actuator; and c) a microcontroller operatively connected to said power supply and said credential device, wherein said microcontroller is configured to selectively operate in either an access mode or a dog mode, wherein said dog mode includes an awake mode; wherein, when in the access mode, said credential device is in a powered state and said actuator is in an unpowered state, wherein, when in said awake mode, said credential device is in an unpowered state and said actuator is kept in a powered state until said awake mode is terminated, and wherein said credential device is placed in said unpowered state after the actuator remains in said powered state for a predetermined period of time.

2. A power control system for use with an electric lock mechanism having an electric actuator, said power control system comprising: a) a power supply configured to receive power from a voltage source and to selectively output an output voltage to the actuator; b) a credential device selectively powered by the power supply, said credential device configured to signal the power supply to output the output voltage to said actuator upon receiving an authorized access code; c) a microcontroller operatively connected to said power supply and said credential device; wherein said microcontroller is configured to selectively operate in either an access mode or a dog mode, wherein said dog mode includes an awake mode; wherein, when in the access mode, the credential device is in a powered state and the actuator is in an unpowered state until said credential device receives said authorized access code after which the actuator is placed in a powered state, and wherein, when in said awake mode, said actuator is placed in a powered state and said credential device is placed in an unpowered state after the actuator remains in said powered state for a predetermined period of time.

3. The power control system of claim 2, wherein said dog mode includes a sleep mode, and wherein, when in said sleep mode, the actuator is in said unpowered state.

4. The power control system of claim 3 wherein said power control system includes a battery to selectively power said credential device, and wherein when in said sleep mode, said credential device is a powered by said battery.

5. A power control system for use with an electric lock mechanism having an electric actuator, said power control system comprising: a) a power supply configured to receive power from a voltage source and to selectively provide an output voltage to the actuator; b) a credential device selectively powered by the power supply, wherein said credential device is configured to detect a credential, and wherein, upon authentication of said credential, a signal is provided to said power supply to provide the output voltage to said actuator; and c) a microcontroller operatively connected to said power supply and said credential device; wherein said microcontroller is configured to selectively operate in either an access mode or a dog mode, wherein said dog mode includes an awake mode; wherein, when in the access mode, said credential device is in a powered state and said actuator is in an unpowered state; and wherein, when in said awake mode, said credential device is in an unpowered state and said actuator is in a powered state, and wherein said credential device is placed in said unpowered state after the actuator remains in said powered state for a predetermined period of time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a side view of a door in a secure condition at a first door position within a door frame and having a portion of the door frame broken away to show a prior art electrically-controlled strike, in accordance with the present invention and operable with a mortise-type dead latch assembly of the door;

(3) FIG. 2, 2a-2j is a composite block diagram of a power control system, in accordance with an aspect of the present invention;

(4) FIG. 3 is a schematic of a power control system having a plurality of actuators and associated credential devices;

(5) FIG. 4 shows current versus time plots for three types of solenoid coils, in accordance with an aspect of the present invention;

(6) FIG. 5 is a schematic of a switched burden resistor array, in accordance with an embodiment of the present invention; and

(7) FIGS. 6A through 6C are each current versus time plots showing actuator activation inrush currents, in accordance with an aspect of the present invention.

(8) Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate currently preferred embodiments of the present invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) Referring to FIG. 1, a typical door 24 is shown in a first, or closed, position. A lock actuator 10 (such as, but not limited to, a door lock actuator) is received in a cavity 12 in a mounting structure 14 (such as, but not limited to, a doorjamb). Actuator 10 includes a housing 16, which may mount its electrical and mechanical components. The electrical components in turn may be electrically in communication by means of wiring 18. Actuator 10, for example, may be in communication with a power supply 20 such as, for example, a 12 or 24 volt circuit, which in turn may be hardwired to the external electric power grid where power supply 20 is configured to receive 115 VAC or 230 VAC line voltage. The actuator 10 may be activated via a credential device 22. This credential device 22 is typically a switch whose contacts selectively actuate the actuator 10. The credential device 22, however, is often incorporated into a control entry device such as a card reader or digital entry keypad, where the actuator is activated after an authorized card is presented to the card reader (or an authorized code is entered into credential device 22). For example purposes, door 24 may be pivotally mounted so that the door 24 is able to move between a closed position and an open position.

(10) Operational control of the power supply 20, actuator 10, and credential device 22 may be provided via a power control system including a programmed microcontroller. With reference to FIG. 2, an embodiment of power control system, for providing power from voltage source 38 to one or more actuators 10, is generally indicated by reference numeral 30. In accordance with this embodiment, power control system 30 includes a power supply 20, one or more actuator drivers 26, 28 (such as, but not limited to a motor driver, a solenoid driver, etc.) used to operate respective actuators 10, a microcontroller 32, and optionally one or more batteries 34, 36 (which may be a 12V battery or a 24V battery).

(11) In one aspect of the invention, power supply 20 may be selected to output either 24 VDC or 12 VDC or both, which is supplied by a voltage source 38 (100 VAC-240 VAC). Power supply 20 may by a two-switch forward converter operating at a pulse-width modulation (PWM) switching rate of 100 kHz or higher. The power control system 30 may indicate the presence of AC voltage through the implementation of an isolator 40 that provides an AC present signal to microcontroller 32. The control system 30 may also indicate the status of AC presence along with various under-voltage, over-voltage, under-current, and over-current conditions, such as through LED outputs 94. These voltage and current conditions include those of, but are not limited to, the actuators, the credential devices, the auxiliary output, the battery charger, and the battery. Furthermore, the voltages and currents of the power control system 30 may also be monitored by microcontroller 32 through voltage and current sensors 44 and 46, respectively.

(12) Power control system 30 may also include batteries 34, 36 to provide the necessary power when power supply 20 is no longer receiving adequate AC source voltage (for instance, during a line voltage interruption or unavailability that may occur through a general power outage or power disruption due to a fire). The power supply 20 may be turned off by signal ECO_PWR 42 which also operates the BYPASS relay 48 to allow either 24V battery 34 or 12V battery 36 to provide the requisite DC voltage to system 30, depending upon the current needs, the battery state-of-charge, or specifications of the power control system 30. To maintain battery charge status, power control system 30 may include battery charger 50 which employ switching regulators to provide the appropriate charging voltages and currents to their respective batteries when AC power is present. If a power failure is detected by microcontroller 32, charger 50 is bypassed by relay 48 and battery current is in turn diverted to actuator drivers 26 and 28 and microcontroller 32. Battery voltages are monitored by microcontroller 32 such that, if a battery voltage falls below a predetermined cut-off threshold, microcontroller 32 dis-engages a relay 52 to disconnect the battery from the circuit.

(13) One or more actuator drivers 26, 28 may be under the control of microcontroller 32 so as to selectively enable activation of a respective actuator 10 upon receiving a drive signal from power supply 20.

(14) As shown in FIG. 3, microcontroller 32 may be configured to operationally monitor and control two distinct actuator drivers 26 and 28 (referred to in FIG. 2 and not shown in FIG. 3) that are associated with the respective actuators 10a and 10b, wherein a respective actuator 10a and 10b is coupled to a respective door 24a and 24b and a respective credential device 22a and 22b. For example, actuator driver 26 may be a motor and actuator 28 may be a solenoid. To that end, microcontroller 32 may include actuator mode settings that establish whether an output will drive a motor or a solenoid. An exemplary table showing certain mode switch settings is shown in Table 1.

(15) TABLE-US-00001 TABLE 1 Switches Outputs M0/M1 #1 #2 0 0 MTR MTR 0 1 MTR SOL 1 0 SOL MTR 1 1 SOL SOL
Signals that engage actuators 10a and 10b, along with the fire alarm input 58 (FIG. 2), are connected to a hardware interrupt and may be processed by interrupt service routines (ISR). Returning to FIG. 2, inputs 60 (/IN#1) and 62 (/IN#2) engage the corresponding actuator connected to outputs 64 (OUT 1) and 66 (OUT 2). As is known in the art, fire alarm input 58 may activate an audible alarm and place microcontroller 32 in a fire alarm mode. Drivers 26 and 28 are configured to each receive a signal from microcontroller 32 to activate a switch (such as a MOSFET, JFET, or BJT, or relay), which provides a conductive path for current through actuator 10a or 10b. Additionally and/or alternatively, microcontroller 32 may operate a solenoid through drivers 26 and/or 28.

(16) As is acknowledged in the art, solenoid driven actuators have long been known for their power inefficiencies. First, it is known that their pull-in current (pick current) is higher than the current needed to hold the solenoid plunger in place (hold current). Therefore, at a minimum, to save energy, the controller should step down the current after a fixed duration of time following application of the pick current. Second, in a Fail-Secure system, the solenoid is often under a power mode as long as the door must remain unlocked. In a Fail-Safe system, the solenoid is in a power mode for as long as the door must remain locked. Thus, in Fail-Safe systems, without further controls, a large amount of power can be wasted while the solenoid remains powered. To that end, microcontroller 32 includes a timer such that, upon signaling solenoid driver 26/28, microcontroller 32 starts a time interval during which a constant voltage is supplied to drive the solenoid. When this time interval expires, micro-controller 32 provides a PWM drive signal of such duty ratio as to cause the hold current to flow through the solenoid coil. To ensure proper operation, at start-up or reset, the microcontroller reads the status of switch settings that establishes the hold-open time intervals, the actuator modes, and the solenoid hold currents. Switch settings and corresponding time intervals are listed in Table 2.

(17) TABLE-US-00002 TABLE 2 Switches Time T10/T11/T12 Interval T20/T21/T22 (sec) 0 0 0 <2 0 0 1 2 0 1 0 5 0 1 1 10 1 0 0 20 1 0 1 30 1 1 0 45 1 1 1 60

(18) Apart from, and in addition to, stepping down the supplied power during pick and hold operations, a further avenue for improving efficiencies when powering a solenoid latch is optimizing the magnitude of the current being supplied to the solenoid during each of the pick and hold operations. Thus, in accordance with an embodiment of the present invention, firmware (not shown) in microcontroller 32 may include a self-calibration routine that accommodates varieties of solenoid coil impedances. This routine may use motor driver 26 outputs to momentarily switch a pulse of current through the solenoid coil (actuator 10a or 10b). The current response is related to the inductance and resistance of the actuator 10a or 10b.

(19) As shown in FIG. 4, if the current is measured at a particular instant in time (t), larger currents are observed for lower impedance coils, wherein curve 67 represents a coil having a relatively low impedance, curve 69 represents a coil having a relatively higher impedance, and curve 68 represents a coil having an impedance between the impedances of the other two. If the current used by a plurality of types of solenoid drivers is observed at the same instant in time, it can be seen that such types of solenoid coil may be readily distinguishable upon interrogation of its instantaneous current values measured at time t. Microcontroller 32 may be populated with a look-up table comprising various solenoid i/t curves. Thus, depending upon the current measured at the selected measurement time t, microcontroller 32 may identify the type of solenoid coil used within actuator 10a or 10b and output the optimum pick current and hold current for that particular solenoid.

(20) As shown in FIG. 5, power control system 30 may further include a driver circuit 70 having a primary switch 74 and a secondary switch 76 that may produce a constant current in solenoid coil 10a and 10b via a pulse-width modulation (PWM) signal from microcontroller 32. Primary switch 74 may be a transistor (such as MOSFET, JFET, or BJT) while secondary switch 76 may be a diode (such as free-wheeling, flyback, or catch diode).

(21) Driver circuit 70 may also include a current-sense amplifier 80, which has two gain resistors 82a and 82b that are used to sense the two components of the load current; the first in primary switch 74 and the second in secondary switch 76. Current sense resistor 86 is connected to primary switch 74 and secondary switch 76. The voltage across current-sense resistor 86 is amplified by current-sense amplifier 80 to provide an analog voltage to micro-controller 32. During the pulse-current test (described above), microcontroller 32 may measure the output voltage of current-sense amplifier 80 at observation time t. As discussed above, this voltage, which is proportional to coil current, is compared to a table of values to determine the coil type. Once the type of solenoid coil is established, microcontroller 32 determines the required duty ratio to establish the optimum pull-in (pick) current and hold current for that specific solenoid.

(22) Turning now to FIGS. 6A-6C, the power control system 30 may be configured for staggered activation of multiple actuator/credential devices. For instance, as discussed above with regard to FIG. 3, power control system 30 may be configured to operate two distinct actuator units 10a and 10b, each having a respective credential device 22a and 22b. As is currently known in the art, should multiple actuators, whether motors, solenoids, or combinations thereof, be activated at the same time, such as during a fire event, current is supplied simultaneously with the current load being additive for each actuator. Should the actuators be solenoids, this additive load requires relatively high pick currents to power each solenoid (the hold currents are likewise additive). To alleviate the need for high pick currents, in accordance with an aspect of the present invention, microcontroller 32 is configured to energize each actuator sequentially, rather than simultaneously. As a result, the inrush current for each actuator is handled separately leading to a smaller required power supply design.

(23) By way of example, FIG. 6A shows a plot 77 of current over time for a single actuator, such as a solenoid coil. As can be seen in FIG. 6A, the current is initially high (i.e., the pick current) and then steps down to a lower hold current. As shown in FIG. 6B, an exemplary current over time plot 79 is shown for simultaneous activation of two actuators as is presently conducted in the art. As can be seen, when comparing FIG. 6A to FIG. 6B, the pick current has doubled while the hold current has also similarly doubled. Thus, the inrush current to pick both solenoids is relatively high. To alleviate the high inrush current, FIG. 6C shows a current over time plot 81 for a staggered activation in accordance with an embodiment of the present invention. As can be seen, a first actuator is activated with a pick current similar to that shown in FIG. 6A. However, rather than simultaneously supply pick currents to each actuator, microcontroller 32 supplies the pick current to a second actuator only after the first actuator pick current time expires, or nearly expires, and its current is stepped down to the hold current. As a result, the pick current of the second actuator is additive with the lower hold current of the first actuator rather than the first actuator's higher pick current. Thus, the peak inrush current demand 83 is less than that for simultaneous pick current actuation 85 shown in FIG. 6B. This, in turn, improves the power efficiency of power control system 30.

(24) In another embodiment of the present invention, microcontroller 32 may further include access/dog switch inputs 90 and 92 (FIG. 2) to selectively control power operation of power control system 30. In the following discussion, Access Mode is when the associated door is continuously locked and a valid authentication access code is needed to unlock the door and, Dog Mode is when the associated door is meant to be kept unlocked, such as during the daytime for a retail store (awake mode), or meant to be kept locked without an expected entry, such as during the nighttime for a retail store (sleep mode).

(25) In this embodiment, Access/Dog inputs 90 and 92, along with the actuator inputs 60 and 62, comprise the access inputs of power control system 30. When active, inputs 60, 62 and 90, 92 initiate the process of an access request which engages or enables outputs 64, 66, which are operatively connected to corresponding actuators. Access control logic is summarized in Table 3 below. Outputs OUT#1 and OUT#2 are for actuators 10a and 10b. Outputs CRED#1 and CRED#2 are for credential devices 22a and 22b. Generally, when in the Access Mode, both credential devices are enabled and the actuators are engaged by their respective inputs. In the Dog Mode, the credential devices are de-activated to reduce energy consumption.

(26) TABLE-US-00003 TABLE 3 Inputs Outputs ACS/DOG 1 2 1 2 3 4 1/0 0 0 0 0 1 1 1/0 0 1 0 1 1 1 1/0 1 0 1 0 1 1 1/0 1 1 1 1 1 1 0/1 0 0 0 0 1 1 0/1 0 1 0 1 1 0 0/1 1 0 1 0 0 1 0/1 1 1 1 1 0 0

(27) By way of example, power control system 30 may be configured to operate in either an Access Mode or in a Dog Mode for a fail-secure system. When in the Access Mode, the actuators 10a and 10b are selected to operate in fail-secure mode. In this manner, when the actuators are de-energized, the latch remains engaged with the strike to secure the door, gate, etc. Additionally, credential devices 22a and 22b are active and using battery power. Thus, power supply is substantially limited only to that required to maintain battery charge. When an access code is entered at credential device 22a or 22b (such as through a keypad, fob, or key card), power control system 30 awakens and energizes actuators 10a and 10b thereby allowing for the withdrawal of the latch. In this manner, roughly 97% of the time, power control system 30 is idle and consuming less than about 100 mW. The remaining roughly 3% of the time requires about 15 W (motors) to about 23 W (solenoids) of power from power control system 30 to actuate actuators 10a and/or 10b. As a result, this power control scheme may equate to greater than 90% energy savings versus existing power supplies.

(28) Power control system 30 may alternatively operate in a Dog Mode for a fail-secure system. During daytime/energized hours, when access is permitted (awake mode), the power control system 30 is awake and power is supplied to actuators 10a, 10b. Credential devices 22a, 22b are unpowered as access is readily permitted and door access does not require any authorization through credential devices 22a and 22b. In accordance with an aspect of the present invention, power control system 30 may automatically enter into its daytime/energized hours mode after power control system 30 senses that the latch has been unlocked (or actuator 10a, 10b has held the respective latch open) for greater than a predetermined period of time, such as, but not limited to, approximately 60 seconds. Conversely, in the Dog Mode when access is not expected (sleep mode), power control system 30 is placed in sleep mode and credential devices 22a, 22b are active and running on battery power. As a result, power output from power supply 20 is limited to only that required to maintain battery charge. In this manner, operating power control system 30 in Dog Mode offers approximately 40% energy savings when compared to current power supply systems.

(29) In accordance with the embodiments of the present invention, and referring again to FIG. 2, power control system 30 may be configured to include at least one of status LED outputs 94, fire alarm reset input 96, TAG connector input 98, serial port 102, microcontroller reset 104, and fault clear input 106. A jumper connection of the Fire Alarm Reset input 96 to the return side of power supply 20 may determine whether a momentary activation of the FIRE input initiates a fire alarm. If not jumpered, a momentary fire alarm input is latched and activates a fire alarm. If jumpered, the momentary signal is not latched and a momentary fire alarm is activated. Status LED outputs 94 provide visual indicators to alert personnel of the status of the output voltages (12 and 24 VDC), the output currents, and the batteries.

(30) TAG connector input 98 may be an interface through which the microcontroller can be programmed. The serial port 102 may facilitate firmware debugging. Microcontroller reset 104 may be provided with a push-button switch that allows system users to reset the microcontroller. Fire alarm reset input may be provided with a push-button switch to allow users to reset the fire alarm. The fire alarm reset switch may be connected in parallel with a possible external fire alarm reset switch.

(31) While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.