GB2215378A

GB2215378A - Keyhole security device

Info

Publication number: GB2215378A
Application number: GB8805508A
Authority: GB
Inventors: Walter Wilson Hugh Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-03-08
Filing date: 1988-03-08
Publication date: 1989-09-20
Anticipated expiration: 2008-03-08
Also published as: GB8805508D0; GB2215378B

Abstract

A keyhole security device for mortise-type door locks, comprising a shutter (14) which can be electrically locked in a position in which it blocks entry to the keyhole (18) of a door-mounted mortise lock on the insecure side of the door, the shutter (14) being locked/unlocked by means of a solenoid operated plunger (24), and being housed in a casing (10) that is adapted to be fixed to the door in such a manner that it cannot be released from said insecure side of the door. The shutter (14) is in the form of a sliding plate which can be displaced vertically against gravity by a manually operated knob (16) for clearing entry to the keyhole (18) in the unlocked state of the shutter. <IMAGE>

Description

KEYHOLE SECURITY DEVICE The present invention relates to mortise locks and to a means of increasing the security of such locks.

Most mortise-type locks are vulnerable to picking by competent experts, access being gained to the interior of the lock by way of the open keyhole itself.

It is an object of the present invention to provide a means of increasing the security of such locks by selectively preventing access to the keyhole, for example at night or as a series step in access security.

According to the present invention there is provided a keyhole security device for mortise-type door locks, comprising a shutter which can be electrically locked in a position in which it blocks entry to the keyhole of a door-mounted mortise lock on the insecure side of the door, the shutter being housed in a casing that is adapted to be fixed to the door in such a manner that it cannot be released from said insecure side of the door.

Preferably, the shutter is locked/unlocked by means of a solenoid operated plunger.

The shutter can be in the form of a sliding plate which can be displaced vertically against gravity by a manually operated knob for clearing entry to the keyhole in the unlocked state of the shutter.

Advantageously, the plunger is adapted to move in a direction perpendicular to the plane of displacement of the shutter plate and is arranged to pass through a hole in the shutter and enter a blind bore in the casing to achieve said locked position of the shutter.

Thus, the shutter cannot be raised to enable access to the keyhole except when the solenoid status has been appropriately switched.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, wherein: Fig. la is a diagrammatic view of the inside of door fitted with a shutter lock in accordance with the present invention; Fig. lb is an exploded section on the centre line of the keyhole in Fig. la; and Fig. lc is a view from the outside of the door showing the shutter lock fitted thereto.

The drawings show very diagrammatically a section of a conventional wooden door edge fitted with a conventional mortise lock, only the keyhole 18 of which is illustrated (Fig. la). The present device comprises a rigid housing 10 having a cavity 12 which receives a planar shutter plate 14 that can be raised against gravity by an external knob 16 to reveal access to the keyhole 18 of the mortise lock on the non-secure side of the door by way of an elongate aperture 20 in the plate 14. A solenoid assembly 22 is attached to the housing 10 and is arranged to be able to push a plunger 24 through the hole 20 in the shutter plate 14 and into a blind hole 26 in the housing. When the solenoid is energised, the plunger 24 is pulsed forward to pass through the hole 20 and engage the blind bore 20 whereby to stop the shutter from being lifted.

The solenoid assembly 22 is disposed in a round hole 28 provided in the door and is attached to the housing 10 by means of threaded screws 30 and a cover 32.

The housing 10 carrying the whole assembly is bolted through the door from the secure side, using blind tapped holes 34 in the housing which receive tapped rods 36 so that tampering from outside cannot enable fixing bolts 38 to be released. Thus, the casing cannot be removed from the insecure side of the door.

The shutter can therefore only be raised when the pin 24 has been withdrawn by change of the solenoid status. Normally, an energise-to-lock solenoid would be used since the opposite version could keep the shutter locked in power failure or coil failure.

Claims

1. A keyhole security device for mortise-type door locks, comprising a shutter which can be electrically locked in a position in which it blocks entry to the keyhole of a door-mounted mortise lock on the insecure side of the door, the shutter being housed in a casing that is adapted to be fixed to the door in such a manner that it cannot be released from said insecure side of the door.

2. A security device as claimed in claim l, wherein the shutter is locked/unlocked by means of a solenoid operated plunger.

3. A security device as claimed in claim 2, wherein the shutter is in the form of a sliding plate which can be displaced vertically against gravity by a manually operated knob for clearing entry to the keyhole in the unlocked state of the shutter.

4. A security device as claimed in claim 2 or 3, wherein the plunger is adapted to move in a direction perpendicular to the plane of displacement of the shutter plate and is arranged to pass through a hole in the shutter and enter a blind bore in the casing to achieve said locked position of the shutter.

5. A keyhole security device for mortise-type door locks, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows

1. A keyhole security device for a mortise-type door lock to be fitted to a door having a secure side and an unsecure side, the device comprising a casing that is adapted to be fixed to the door from the secure side by bolts received in blind fixing recesses in the casing whereby the casing cannot be released from the insecure side of the door, a sliding shutter which can slide within the casing between a first position in which it blocks entry from the insecure side of the door to the keyhole of a mortise lock mounted in the door and a second position in which access to the keyhole is allowed the shutter being adapted to be locked/unlocked in said first position by means of the plunger of a solenoid, adapted to be received behind the casing and within a recess in said door.

2. A security device as claimed in claim 1 wherein the shutter is in the form a sliding plate which can be displaced vertically against gravity by a manually operated knob for clearing entry to the keyhole in the unlocked state of the shutter.

3. A security device as claimed in claim 2, wherein the plunger is adapted to move in a direction perpendicular to the plane of displacement of the shutter plate and is arranged to pass through a hole in the shutter and enter a blind bore in the casing to achieve said locked position of the shutter.

4. A keyhole security device for a mortise-type door lock to be fitted to a door having a secure side and an unsecure side, the device comprising a shutter which can be electrically locked in a position in which it blocks entry from the insecure side of the door to the keyhole of a door-mounted mortise lock, the shutter being housed in a casing that is adapted to be fixed to the door in such a manner that it cannot be released from said insecure side of the door and being in the form of a sliding plate which can be displaced vertically against gravity by a manually operated knob for clearing entry to the keyhole in the unlocked state of the shutter, the shutter being locked/unlocked by means of a solenoid operated plunger which is adapted to move in a direction perpendicular to the plane of displacement of the shutter plate and is arranged to pass through a hole in the shutter and enter a blind bore in the casing to achieve said locked position of the shutter.