GB2096687A - Electric strike - Google Patents

Abstract

A keeper for a door-lock comprises a casing 20 having an opening 24, through which the extended door lock bolt may pass and a detent 30 movable by the actuation of solenoid 46 from the blocking position shown to a release position. The detent may be held in either the blocking or the release position by the engagement of plate 62 with recess 64 or 66 respectively in shaft 58, the plate 62 being mounted on shaft 80, spring urged to its engaging position, and removed from it by solenoid 60. The device is unlocked by a switch which instantly actuates solenoid 60 and, after 1 DIVIDED 2 second, solenoid 46. It is locked by a quick push on the switch which releases lock plate 62, allowing detent 30 to fall. In both actions the lock plate automatically engages in the appropriate recess to hold the detent 30 in its final position. <IMAGE>

Description

SPECIFICATION Electric strike This invention relates to an electric strike, for example, for mounting on a door frame, and provided with a lock means so as to assure locking and unlocking of the electric strike.

Various constructions of electric strikes are used in lock mechanisms for doors. Among them, one such electric strike having a movable strike is known. For example, a lock mechanism is known, in which the strike is pivoted to a housing opening and is always biased by a spring in a closing direction of the opening. However, in such a lock mechanism, the strike is returned by the spring action to the closed state once the door is opened.

Such a lock necessitates the use of a key, in order to open and close the door. It is therefore inconvenient and even dangerous in case of, for example fire or other emergencies, or when a number of people wish to pass through.

In addition a lock in which, when the door is opened, a stopper is released to stop the movement of the strike and in which this state is maintained for a predetermined period after the lock is operated, is also known. During this period the strike is rotated to open and close and door.

However, with such a lock, if the door is left open for some time, the predetermined period having elapsed the stopper will come to a locked position.

Therefore, a state in which the door lock bolt abuts against the strike and prevents the door from closing may arise, where it is desired to close the door.

Thus, according to the present invention there is provided an electric strike for a lock having a door lock bolt, said strike comprising a wall element forming a housing for surrounding the door lock bolt at a protruding position, an opening formed on said wall element so that the door lock bolt in the protruding position can enter the housing or can be retracted from said housing, a strike latch for opening and closing said opening, and a lock means for releasably locking said strike latch when the strike latch is at a position for closing said opening and at a position for opening said opening.

In an embodiment of the present invention an electric strike is provided which can select the locking or unlocking state by electrically controlling the operation of the strike latch and the lock means.

Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an electric strike according to an embodiment of this invention, which is mounted to a door frame.

Fig. 2 is a perspective view of a strike of an embodiment of the present invention in a disclosing or open position.

Fig. 3 is a perspective view showing the strike dismantled.

Fig. 4. is a perspective view of a wall element of the embodiment of Figure 2 with the strike in a closed position.

Fig. 5 is a longitudinal sectional view of an embodiment of the electric strike according to this invention.

Fig. 6 is an enlarged sectional view of a solenoid portion.

Fig. 7 is a sectional view taken along 7-7 line of Fig. 5.

Fig. 8 is an enlarged perspective view of a lock means.

Fig. 9 is a sectional view of a portion of a lock means showing another embodiment thereof.

Fig. 10 is a schematic diagram of the electric circuit of an embodiment of the present invention.

Fig. 11 is a schematic diagram illustrating another embodiment of the invention.

Fig. 12 is a diagram of an electric circuit designed on the basis of the electric circuit diagram shown in Fig. 10.

Fig. 13 is another embodiment of an electric circuit designed on the basis of the electric circuit diagram shown in Fig. 10.

Fig. 14 is an electric circuit diagram of an embodiment of the electric strike according to this invention in which a plurality of switching means are provided therein.

Referring to Fig. 1, a door 10 is provided with a well known lock having a door lock bolt 1 6 (shown with two-dot chain line in Fig. 5) which engages by means of a knob 12 or a key (not shown) inserted in a key hole 14.

Referring to Fig. 2 and Fig. 3, a wall element comprises a casing 20 provided for positioning opposite the door lock bolt of a door frame 1 8, and a housing 22 for surrounding the door locl < bolt protruding into a portion of the casing. In the above housing, an opening 24 is provided through which the door lock bolt can enter or be retracted from the housing while in its protruding state.

Within the casing, a strike latch is provided, which in a locked state, controls the door lock bolt so as to prevent its movement in the opening direction of the door through the opening 24. The stril < e latch is provided with a movable portion 28 for insertion into a fixed portion 26 forming the housing, in the vertical direction in the drawing.

The movable portion has a block wall 30 whose section is substantially channel shaped. One end of the block wall is connected to a connecting plate 34 having a protruding piece 32. The fixed portion is provided with insertion holes 36, 36 for guiding the movement of the block wall. The fixed portion has flanges 38, 38, which are fitted to a front plate 42 of the casing by screws 40, 40 (Fig.

5). The front plate may be provided with an armour plate 44. The block wall lies at a remote position from the housing in an unlocked or a disclosed state (Fig. 2) and lies at a position within the housing in a locked or closed state (Fig. 4). The opening 24 of the housing is located in a mutually reverse position according to whether the door is opened inwardly or outwardly, or opened and closed in righthanded or lefthanded manner, or according to the way of fitting. As shown in Fig. 3, however, the insertion holes 36 are provided on both the upper and the lower wall faces of the fixed portion so that it can be used in either state, by fitting either way up. However, the hole in the lower wall face of the fixed portion will not always be provided.

The strike latch has a solenoid 46 for operating the movable portion. A lock means for locking the movable portion at a position to which it has moved is provided in connection with the solenoid. Any type of solenoid may be used for the solenoid 46. In the drawing, one coil 48 and another coil 50 are respectively wound on a spool 52 and supported by an inner cylinder 54. The inner cylinder 54 is made of non-magnetic material such as, for example, aluminum, copper or synthetic resin and both ends of the inner cylinder are joined to a supporting frame 56 made of magnetic material such as, for example, iron, nickel, and silicon steel plate, so as to lessen the leakage flux by means of the supporting frame.

One end of a plunger 58 movable by the solenoid 46 is connected to the protruding piece 32 of the block wall by connecting means, for example, screw, rivet or force fit. The lock means includes a stopper 62 (Fig. 8) provided for movement according to the excitation and the deactivation of another solenoid 60, and the plunger is provided with two necks 64 and 66, which are spaced from each other by an interval nearly equal to the travel length of the block wall.

The solenoid 60 is mounted on one of the frame sides 68 perpendicular to the longitudinal direction of the supporting frame 56 of the solenoid 46. The solenoid 46, the solenoid 60 and the block wall are so arranged that they form a line in the longitudinal direction as a whole within the casing, and are easily received within narrow space of the door frame.

The lock means has a movable contact piece 70 which is magnetically attracted to a magnetic pole of the solenoid 60. The movable contact piece has two wings 72, 74 which make an angle with each other somewhat larger than a right angle. The wing 74 is positioned so as to face the magnetic pole 76 of the solenoid 60 and the wing 72 is positioned so as to face the front plate 42 of the casing, between which a spring 78 is interposed. Thus the wing 74 is biased in the direction of parting from the pole 76 (in the direction of the stopper engaging with the neck of the plunger 58). At the base of the two wings, one end of a rod 80 is connected by, for example, welding, adhesion, or force fit. The rod 80 is inserted in small holes (not shown) respectively provided in the frame side 68 of the supporting frame 56 and in another frame side 82 which is opposite the frame side 68.Thus, the rod 80 is pivoted to the supporting frame 56. The end portion of the rod 80 is positioned between the frame side 82 and the housing, and the stopper 62 is connected to the end portion of the rod in a manner similar to that by which it is connected to the wings. The stopper 62 has a hole 84 through which the plunger extends. The hole 84 is oblong shaped so that when the wing 74 is attracted to the magnetic pole, the stopper 62 moves and its edge engages the neck of the plunger. As shown in Fig. 9, on the side on which the rod of the stopper is connected, a sleeve 86 is provided on the under face of the stopper so that a portion of the peripheral edge of the oblong hole will extend outside and a protrusion 88 is provided on a portion of the sleeve 86. Thus, the plunger 58 may be smoothly moved when the lock means are shifted from locked to unlocked state or vice vera.

In Fig. 10, a block diagram illustrates an electric control section for driving the solenoid 46 and the solenoid 60.

The electric control section comprises a delay circuit 92 whose activation is controlled by a switching means 90. The output terminal of the delay circuit 92 is electrically coupled with the coils 48, 50 of the solenoid 46 through a buffer circuit 94 and a driving relay 96. The solenoid 60 is wired so as to be excited as soon as the switching means 90 is closed, therewith activating the delay circuit 92, and after a predetermined delay time (about 5 to 0.2 second, preferably about 0.5 second) has elapsed, the voltage level of the output terminal of the delay circuit will be changed (from low potential to high potential or vice versa). The change is transmitted to the driving relay 96 through the buffer circuit so that the driving relay will respond to the change.

When the driving relay operates, electric current is supplied to the coil of the solenoid 46 from a power supply, so that the plunger of the solenoid is raised. Further, should a circuit having sufficient output electric power for direct drive of the solenoid 46 be used as the buffer circuit, the driving relay can be eliminated. Where the driving relay can be directly driven the output of the delay circuit, the buffer circuit would not always be provided.

For the delay circuit, as the CR timer type, for example, logic IC of TTL, CMOS and the like, IC for timer, or a combination of semiconductor elements, such as, for example transistor, FET (field effect transistor), PUT (programmable unijunction transistor), SCR (silicon controlled rectifier) triac and the like, with the time constant circuit comprising resistor and capacitor may be used, and as the counter type, a combination of oscillation circuit with other circuit, for example, flip-flop, IC for counter, or shift register may be used. Also, to use battery as power source, to obtain direct current by rectifying alternating current power supply or both of them may be used together.

Now, as switching means 90, a button type switch (not shown) is provided near the door, by which the operation of locking and unlocking are effected, which cases are described as follows.

In a locked state, the block wall of the movable portion is situated at a position shown in Fig. 4.

When the switch is closed by the operation of the button type switch, first the solenoid 60 is excited and the engagement between the neck 64 of the plunger 58 and the stopper 62 is disengaged. Then since the plunger is raised by the excitation of the solenoid 46, the block wall is also raised and moved outside the housing as is the case in Fig. 2.

When the button type switch is opened, the solenoids 46, 60 are deenergized so that, the stopper 62 engages the neck 66 and the block wall is locked at a position outside the housing. As a result, since the lock bolt is free in the door opening direction, the door can be opened.

Thereupon, since the block wall is locked at a position outside the housing, even though a number of people or firemen open and close the door one after another, the door is not locked. If, after closing the door, the button type switch is closed again and before the elapse of the set time of the delay circuit, the button type switch is opened, then the solenoid 60 only is excited and the stopper will be disengaged from the neck 66, so that the plunger is free to move and the block wall will drop by its own weight, returning to the position shown in Fig. 4. The plunger is locked again at this position by the engagement of the stopper with the neck 64 and the block wall is now in the locked state. Therefore, there is no fear of the lock being forced by an intruder.In the drawing, the block wall is constructed so that it will drop by its own weight when it shifts from the unlocked state to the locked state. However, it may be moved by, for example a spring in the direction of the locked state. When aluminium is used for the inner cylinder, the switching means is operated and when power supply to a lead connecting to the solenoid 60 is cut off, the deactivation can be effected with some delay of the solenoid 46 to be later than the deactivation of the solenoid 60. In this way, a movement time-lag between the stopper and the plunger can be obtained, thus surely effecting locking. Further, by providing a capacitor in parallel with the driving coil of the driving relay or by providing a capacitor in parallel with the coil of the solenoid, the deactivation can be effected with some delay of the solenoid 46 similar to the above mentioned cause.

The distance of block wall movement may be determined according to the breadth of the door lock bolt, and a lock generally used, a construction such as that shown in the Fig. 10 will be sufficient for operation. However, where it is applied to a lock having a specially broad door lock bolt, one such as that in which the solenoid 46 has a plurality of coils is used, in which by exciting these coils with a time difference, the necessary movement length for such a broad door lock bolt can be obtained. An example of block diagram for the above purpose is shown in Fig. 11.

In the latter part of the delay circuit 92, a one shot multivibrator 100 and a flip-flop 102 triggered by the change of output state of the one shot multivibrator are provided. A buffer circuit 94a whose operation is controlled according to the change of output state of the flip-flop is provided in combination with a driving relay 96a, and another buffer circuit 94b whose operation is controlled according to the change of output state of the one shot multivibrator is provided in combination with another driving relay 96b.

Further, other than this construction, similiar working may be effected by various combinations of known electronic circuits.

In the present construction, the current supply to the coil 50 is controlled by the driving relay 96b and current supply to the coil 48 is controlled by the driving relay 96a and this operation wil be described below.

When the one shot multivibrator is triggered by the change of output state of the delay circuit, the coil 50 will be excited during the width of output pulse of the one shot multivibrator and the plunger 58 will be raised. When the flip-flop is triggered by the trailing edge of the output pulse of the one shot multivibrator, the excitation of the coil 50 is released and the coil 48 is excited to raise the plunger higher.

In Fig. 12, an example of an electric circuit constructed on the basis of the block diagram in Fig, 1 0 is shown.

The delay circuit 92 has a time constant circuit comprising a NOR gate 104, a NOR gate 106 working as an invertor, a capacitor 108 and a resistor 110, one of input terminals of the NOR gate 104 is connected to the output terminal of the NOR gate 106, and another of the input terminals is grounded. The resistor 110 and one of terminals of the capacitor 1 08 are respectively connected to the input terminal of the NOR gate 106 and the other terminal of the capacitor is grounded, and that of the resistor is connected to a lead 112.

The buffer circuit 94 has a transistor 114 and a transistor 11 6, and the driving relay 96 is connected between collectors of these transistors and the lead 112. The emitter of the transistor 11 6 is grounded and the base of the transistor is connected to the emitter of the transistor 114.

The output of the NOR gate 104 is connected to the base of the transistor 11 4 through a resistor 118. The positive terminal of a power supply 98 is connected to the lead 112 through a switching means 90 as well as connected to one end of the coil of the solenoid through the contact of the driving relay. The other end of the coil and the negative terminal of the power supply are grounded. Further, a diode 1 20 connected in parallel with the resistor 110 and a resistor 122 connected between the lead 112 and earth are provided so as to discharge in a short time the electric charge on the capacitor 108, when the switching means are operated and the power supply to the lead 112 is cut off. A diode 124 is provided so as to avoid any excessive voltage on the transistors 114, 11 6.

When the switching means are operated and the lead is connected with the power supply, the solenoid 60 is excited and the locking of the lock means is released. The capacitor 108 of the time constant circuit is charged and when its terminal voltage reaches the threshold level of the NOR gate 106, the output of the NOR gate 106 becomes "0". So that, the output of the NOR gate 104 becomes "1", therewith the transistor 114 and the transistor 11 6 are placed in the conductive state. As the result, the driving relay is excited, closing its contact, and current is supplied from the power supply 98 to the coil of the solenoid, thus the block wall is raised together with the plunger.When the operation of the switching means is released and returned to the original state, the solenoid 60 is deenergized and the edge of the hole of the stopper engages with the neck 66 of the plunger, thereby locking the block wall in the raised state.

Another embodiment which works in a similar manner two that of Fig. 12 is shown in Fig. 13. In this embodiment, an IC 126 is used as a delay circuit. In the IC, for example, trade name NE-555 of U.S. Signetics Co., trade name ICM 7555 of U.S. Intersil Co. and other ICs for timers having similar functions may be suitably used.

A time constant is provided by a resistor 128, a variable resistor 130 and a capacitor 132 at No. 4 terminal of the IC, and when the terminal voltage of the capacitor becomes nearly equal to the voltage of power supply, the state of No. 3 terminal of the IC becomes "1". No. 3 terminal is connected to the base of a transistor 134 which works as a buffer circuit. No. 8 terminal of the IC is a power supply terminal which is connected to the lead 112. No. 5 terminal is grounded through a capacitor 136 and No. 1 terminal, No. 2 terminal and No. 6 terminal are directly grounded. The working of the circuit is nearly the same as in the case of the Fig. 12, and when the switching means are closed, the solenoid 60 is excited, therewith the timer provided by the IC will start.

After elapse of a predetermined delay time, No. 3 terminal of the IC becomes "1", therewith the transistor 134 becomes conductive. As the result, a driving relay 96 is excited to close its contact, and the solenoid 46 is excited, thereby achieving the same result as in the case of Fig. 1 2. The delay time is adjustable by adjusting the variable resistor 1 30.

For the circuits of Fig. 10 to Fig. 12, a push button type switch, a limit switch and other mechanically operating switches, a mechanical contact relay or a non-contact relay and other electronic circuit having similar function may be used as the switching means. For example, if a bimetal type fire detecting element or a noncontact relay responsive to the change of state of a heat sensitive element is used as the switching means, an electric strike capable of automatic unlocking in case of fire can be obtained.Further, a plurality of switching means may be provided, for example, as shown in Fig. 14, in which a diode 138 is connected such that the current flows from the lead 112 to the solenoid and a switching means 140 is provided between the terminal of the solenoid 60 and the positive terminal of the power supply. Then -one can respectively use this switching means for locking operation and switching means 90 for unlocking operation, and it becomes unnecessary to pay attention to open the switch means before the elapse of the set time of the delay circuit at the time of locking as in the case of the embodiment described above, thus the time from closing to opening of the switching means for locking operation may be set optionally.

Further, when a mechanical contact relay or a non-contact relay by means of semiconductor element is used for the switching means, and a control device which employs a micro-computer or constructed with a logic circuit is combined so that switching means is operated when, for example, predetermined memorized number is entered via a keyboard 1 42 (Fig. 1) provided near the door, providing an electric strike which needs no key. Further, it is possible to achieve remote control by providing a switching means responsive to the output of an optical sensor, such as, for example, a photo-transistor, CdS, ultrasonic sensor or radio receiver, to unlock or lock when buzzer sound or acoustic signal of specific frequency is given; and to provide various constructions.

Claims (6)

1. An electric strike for a lock having a door lock bolt, said strike comprising a wall element forming a housing for surrounding the door lock bolt at a protruding position, an opening formed on said wall element so that the door lock bolt in the protruding position can enter the housing or can be retracted from said housing, a strike latch for opening and closing said opening, and a lock means for releasably locking said strike latch when the strike latch is at a position for closing said opening and at a position for opening said opening.

2. An electric strike according to Claim 1, wherein said strike comprises a clock wall movable between a position within the housing and at a position outside said housing.

3. An electric strike according to Claim 2, wherein said block wall of the strike latch is provided to move along the wall element; a plunger is connected to said block wall; said plunger is respectively provided with two necks having an interval therebetween which is substantially equal to moving length through which said block wall is movable; and said lock means comprises a stopper for engaging said necks.

4. An electric strike according to Claim 3, wherein the strike latch comprises a solenoid for moving the plunger connected to the block wall; the lock means comprises a solenoid for moving the stopper, a delay circuit is provided which is activated when current is supplied to the solenoid of said lock means so that said block wall moves after the locking of said block wall is released; a switching means is provided to control the activation of said delay circuit and the current supply to the solenoid of said lock means; and the output terminal of said delay circuit is electrically coupled with the solenoid of said strike latch so that current can be supplied to the solenoid of said strike latch according to a change in output state of said delay circuit.

5. An electric strike for a lock having a door lock bolt comprising a housing for receiving the protruding door lock bolt which housing has an opening and is defined by a wall element; a block wall for opening and closing the opening of said housing, the block wall being movable along said wall element; a solenoid for moving said block wall arranged on the line of movement of said block wall; another solenoid located adjacent said solenoid for operating a stopper for locking the movement of said block wall to lock said block wall at a closing position and at an opening position of said opening.

6. An electric strike for a lock substantially as herein described with reference to Figures 2 to 4 with or without reference to any of Figures 1 and 5 to 14 of the accompanying drawings.