US3921423A

US3921423A - Tamper-proof door lock assembly

Info

Publication number: US3921423A
Application number: US485775A
Authority: US
Inventors: Jesse R Hollins
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-07-05
Filing date: 1974-07-05
Publication date: 1975-11-25
Anticipated expiration: 1992-11-25

Abstract

A door lock assembly including a dead bolt and a knob on the inside of the door for controlling the extension and retraction of the dead bolt. Means secured to the inside surface of the door selectively prevents said dead bolt control knob from rotating to retract said dead bolt from an extended position whereby said door cannot be opened unless said means is positioned so as not to interfere with rotation of said knob to retract the dead bolt.

Description

United States Patent Hollins 1 Nov. 25, 1975 [54] TAMPER-PROOF DOOR LOCK ASSEMBLY 3,423,974 1/1969 Bernsley 70/416 Inventor: Jesse R. Quins, 4O Stoner Ave. 3,748,882 7/1973 Dusault et al 70/416 Great Neck, N.Y. 11021 Primary ExaminerAlbert G. Craig, Jr. [22] Filed: July 5, 1974 21] Appl. NO.2 485,775 [57] ABSTRACT A door lock assembly including a dead bolt and a [22] 70/]11065,B7O/447 knob on the inside of the door for controlling the 2 2 tension and retraction of the dead bolt. Means secured 1 o earc l DI 5 to the inside surface of the door selectively prevents 5 R f d said dead bolt control knob from rotating to retract 1 e erences said dead bolt from an extended position whereby said UNITED STATES PATENTS door cannot be opened unless said means is positioned 756,064 3/1904 Sherman 70/429 so as not to interfere with rotation of said knob to re- 840,711 1/1907 Puttcamp et al... 70/429 tract the dead bolt.

1,700,135 1/1929 Lanes 70/416 3,263,462 8/1966 Suroff et a1. 70/447 1 Claim, 5 Drawing Figures US. Patent Nov. 25, 1975 3,921,423

TAMPER-PROOF DOOR LOCK ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention Tamper-proof door lock 2. Description of the Prior Art Many doors include a mortice-type door lock mechanism. A mortice-type door lock mechanism includes a door latch which is secured to the door. A lock plate is located on the door frame and includes a latch receptacle for the latch. When the latch is received within the latch receptacle the door cannot be opened. On the other hand, when the latch is retracted from the latch receptacle, the door can be opened. Usually a lock cylinder is provided so that if the appropriate key is inserted thereinto from the outside of the door the latch can be withdrawn by rotating the key enabling the door to be opened. The door. of course, can be opened from the inside by rotating the inside door knob.

A mortice'type lock unit includes two pins within the lock mechanism with each pin extending to the lateral edge of the door. By pushing one of the pins the latch cannot be retracted upon the outside door knob being rotated. By pushing the other pin, the latch is retracted upon the outside door knob being rotated.

While the mortice-type lock hereinbefore described provides an adequate method of securing a door, the lock can be picked, i.e., illicitly opened by using a mas ter key or lock picking tool to open the lock cylinder.

In an attempt to prevent illicit opening of a door, many people use a dead bolt lock assembly which acts as an additional means for preventing the illicit opening of the door. The dead bolt lock assembly includes a dead bolt which can be extended outwardly from a door into a dead bolt receptacle in the door frame by rotating a knob located on the inside surface of the door. A lock cylinder is provided so that the dead bolt can be retracted by a person extending a key into said lock cylinder from the outside surface of the door. When the dead bolt is retracted, the dead bolt assembly does not prevent the door from being opened. However, when the dead bolt is extended so as to extend into the dead bolt receptacle, the door cannot be opened even if the mortice-type lock latch is retracted, i.e., is not received in the latch receptacle.

A problem that exists with a dead bolt type lock assembly is that by use of a pass key or lock picking tool it is still possible for a person to illicitly retract the dead bolt so that it is no longer in the dead bolt receptacle whereby if the latch is retracted the door can be illicitly opened.

SUMMARY OF THE INVENTION 1. Purposes of the Invention It is an object of the present invention to provide improved means for securing a door against illicit opening.

Another object of the present invention is to provide a tamper-proof door lock which prevents the illicit retraction ofa door dead bolt from the dead bolt receptacle in the door frame.

Another object of the present invention is to provide apparatus for precenting the illicit retraction of a dead bolt from the dead bolt receptacle which apparatus is controlled by means attached to the inside surface of the door.

Still another object of the present invention is to provide means for preventing a key from turning the lock mechanism thus retracting the dead bolt from its receptacle wherein said means is attached to the inside surface of the door and can easily be placed in selective operation.

Yet another object of the present invention is to provide apparatus for preventing the illicit retraction of a door dead bolt from a door receptacle wherein said apparatus can be attached to the inside surface of a door and can be economically manufactured and is easy to utilize Other objects of the invention in part will be obvious and in part will be hereinafter pointed out.

2. Brief Description of the Invention According to the present invention. the foregoing as well as other objects are achieved by a dead bolt knob lock which consists of a housing that is affixed to the inside surface of a door. Affixed to said housing is a swing plate which has a first position wherein said plate is spaced from the dead bolt knob. In the second position the plate is located immediately above the dead bolt knob and prevents the same from rotating so that even if a key or tool is inserted into the lock cylinder for the dead bolt from outside of the door, the dead bolt cannot be rotated inasmuch as this is prevented by abutment by said dead bolt knob with said plate.

The invention accordingly consists in the features of construction. combination of elements and arrange ment of parts which will be exemplified in the device hereinafter described and of which the scope of application will be indicated in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a partially broken front elevational view of a conventional mortice-type lock and a conventional dead bolt lock assembly;

FIG. 2 is a side plan view of a door having a conventional mortice-type lock assembly and a conventional dead bolt lock assembly utilizing the dead bolt control mechanism of the present invention;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged sectional view taken substantially along the line 4-4 of FIG. 3; and

FIG. 5 is an enlarged sectional view taken substantially along the line 55 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 of the drawings a conventional prior art mortice-type lock and dead bolt lock assembly structure 10 on door 12 is shown. Door 12 cooperates with door frame 14 in the conventional manner. A door knob 16 is provided on the outside of the door which is shown in FIG. 1 of the drawings. Door knob 16 is affixed to mortice lock assembly housing 18. A latch 20 is provided. Latch 20 can be extended and retracted as will hereinafter be described. Mortice-type lock assembly includes

pins

22 and 24. Upon pin 22 being depressed rotation of knob 16 results in latch 20 being retracted so that the door can be opened. On the other hand, when pin 24 is depressed rotation of the door knob on the outside of the door does not result in latch 20 being retracted.

Secured to door frame 14 is a lock plate 26. Screws 28 and 30 extend through clearance holes in lock plate 3 26 and are in threaded engagement with frame 14 to prevent lock plate 26 from moving. Lock plate 26 includes a latch receptacle which receives latch in the conventional manner.

A dead bolt assembly 32 includes a knob 34 and a dead bolt 36. Plate 26 includes an opening to which a dead bolt receptacle '38 extends. With knob 34 in the vertical position shown in FIG. 2. dead bolt 36 is in the retracted position. i.e.. said dead bolt does not extend into dead bolt receptacle 38. On the other hand. with knob 34 rotated clockwise ninety degrees from the position shown in FIG. 2, looking at the rear of said dead bolt assembly. dead bolt 36 is in receptacle 38 so as to prevent door 12 from being opened.

A key and lock cylinder arrangement is provided and includes a key receiving opening 41 on the outside of door 12. Upon the appropriate key being received in key receiving lock cylinder opening 41 and rotated. dead bolt 36 can be retracted and during said retraction knob 34 is rotated. A lock cylinder 44 is provided and includes an opening for receiving a key on the outside of the door so that upon the proper insertion of a key in said lock cylinder and rotation thereof the latch 20 can be retracted as necessary.

The aforedescribed structure is conventional and enables a person to use two locking means to secure a door. However. a pass key or pick may be used by someone to retract dead bolt 38 by being inserted in lock cylinder opening 41. Similarly. a pass key or pick may be inserted in lock cylinder 44 to retract latch 20. If all of the foregoing is done. door 12 can be illicitly opened.

In the drawings a dead bolt knob lock housing is shown and includes

sections

48 and 50 which extend perpendicularly away from the door.

Sections

48 and 50 are parallel to each other and spaced apart from each other and joined at their inside portions by a verti cal side. Section 48 includes a central opening 52. In a similar fashion. section 50 includes a central opening 54. It is to be appreciated that openings 52 and 54 are in'registry with each other with opening 52 being larger than opening 54. A rivet 56 extends through openings 54 and 52 and includes a head 58 which rests on the outer surface of section 48 and a curled-over end 60 which abuts the outer surface of section 50. A compression spring 62 surrounds rivet 56 in opening 52 and the upper end of said spring abuts head 58. A swingable pivot plate 64 is provided and a portion of said plate extends into the space between

sections

48 and 50. Pivot plate 64 includes an opening through which rivet 56 extends.

The bottom end of compression spring 62 abuts pivot plate 64 so as to urge said pivot plate in contact with section 50 to prevent said pivot plate from freely pivoting. Pivot plate 64 is generally rectangular in configuration and can be swung between the alternate positions shown in dotted and solid lines in FIG. 4.

Pivot plate 64 when in the solid position shown in FIG. 4 is above a section of knob 34 so as to prevent the same from being rotated in a counterclockwise direction from the horizontal position in which the dead bolt is extended so as to move the dead bolt from a locking position to a non-locking position. Extending through I 4 76 extend through section 48 with the ends of said bolt clearance hole furthest from the door plate each being countersunk. Screws 78 and 80 extend through

bolt clearance holes

74 and 76 respectively and are in threaded engagement with the door.

In attaching the dead bolt knob lock to door 12 care must be taken so that said knob lock is positioned whereby plate 64 can be swung so that a portion of said plate is immediately above a section of knob 34 when the knob is in the horizontal position (see FIG. 5).

If a person wishes to insure that the dead bolt is placed in a locked condition and cannot be unlocked. knob 34 is rotated to the horizontal position shown in FIGS. 3, 4 and 5 whereby the dead bolt is extended and received in dead bolt receptacle 38. Plate 64 is then swung to the position shown in solid lines in FIG. 4 overlaying a portion of knob 34 and thereby preventing the knob from being rotated in a counterclockwise direction and retraction of the dead bolt.

Even if somebody has the key for lock cylinder 40 they still will not be able to retract the dead bolt inasmuch as knob 34 is prevented from rotating by plate 64. Obviously a pick will be of no assistance to a person seeking to illicitly retract the dead bolt inasmuch as even if the pick is successfully used to rotate lock cylinder 40, knob 34 cannot rotate since it will abut plate 64 thereby preventing the dead bolt from being retracted.

When a person leaves the premises in which door I2 is installed. plate 64 is swung to the position shown in dotted lines in FIG. 4, i.e. out of the way of knob 34. Thusthe person upon returning to the premises can use his key to open lock cylinder 40 and rotate knob 34 to retract the dead bolt.

The parts may be made of suitable materials such as metal. plastic. etc.

The invention accordingly consists in the features of construction. combination of elements and arrangement of parts which will be exemplified in the device hereinafter described and of which the scope of application will be indicated in the appended claims.

Having thus described the invention there is claimed as new and desired to be secured by Letters Patent:

1. A door lock assembly comprising a door. a door frame. a dead bolt assembly secured to said door. said dead bolt assembly including a dead bolt. an oblong knob having an elongated axis on the inside surface of said door and rotatable for controlling the extension and retraction of said dead bolt, a lock cylinder having an opening on the outside surface of said door for receiving a key for controlling the extension and retraction of said dead bolt. said door frame including a dead bolt receptacle. a housing affixed to said door on the inside surface thereof. said housing including two spaced apart parallel sections with a gap extending between said sections. a first of said sections including an opening extending there through, a second of said sections including an opening extending there through and in alignment with said opening extending through said first of said sections, means bolting said first section to said door and means bolting said second section to said door, a member extending through said openings. a pivot plate having an opening and pivotable about said member in said gap, a spring having two ends surrounding said member and affixed at one end of said member and abutting said pivot plate at said other end whereby said pivot plate is prevented from freely moving, said pivot plate having a flat rectangular configuration, said pivot plate having a first and second position, said pivot and in said second position spaced from said knob to enable said knob to be rotated. said pivot plate in said first and second positions being in a single plane.

Claims

1. A door lock assembly comprising a door, a door frame, a dead bolt assembly secured to said door, said dead bolt assembly including a dead bolt, an oblong knob having an elongated axis on the inside surface of said door and rotatable for controlling the extension and retraction of said dead bolt, a lock cylinder having an opening on the outside surface of said door for receiving a key for controlling the extension and retraction of said dead bolt, said door frame including a dead bolt receptacle, a housing affixed to said door on the inside surface thereof, said housing including two spaced apart parallel sections with a gap extending between said sections, a first of said sections including an opening extending there through, a second of said sections including an opening extending there through and in alignment with said opening extending through said first of said sections, means bolting said first section to said door and means bolting said second section to said door, a member extending through said openings, a pivot plate having an opening and pivotable about said member in said gap, a spring having two ends surrounding said member and affixed at one end of said member and abutting said pivot plate at said other end whereby said pivot plate is prevented from freely moving, said pivot plate having a flat rectangular configuration, said pivot plate having a first and second position, said pivot plate in said first position abutting a portion of said oblong knob parallel to said elongated axis and preventing said knob from rotating to retract said door bolt from an extended position to a retracted position, and in said second position spaced from said knob to enable said knob to be rotated, said pivot plate in said first and second positions being in a single plane.