US3652113A

US3652113A - Door latch assembly with pushbutton actuation

Info

Publication number: US3652113A
Authority: US
Inventors: Fortune Odend Hal; Harry A Jordan
Original assignee: Jamison Door Co
Current assignee: Jamison Door Co
Priority date: 1969-08-25
Filing date: 1969-08-25
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: JPS4910880B1

Abstract

A door latch assembly is provided with a pushbutton actuation to release a lever plate from a pawl so that a door can be opened by free rotation of the pawl relative to a keeper. The lever plate is pivotally mounted within a housing which is secured with a base plate to the surface of the door, and the lever plate is normally urged into latching engagement with the pawl. The pushbutton contacts one end of the lever plate so as to move it out of engagement with the pawl. A separate releasing means, operable from an opposite side of the door from the position of the pushbutton means, contacts an opposite end of the lever plate so as to release the lever plate from the pawl without affecting the position of the pushbutton means. Thus, it is possible to release the door from the inside of a room even if the pushbutton means has been locked in a fixed position.

Description

1111110 tea 1111 -U01e11d11a1eta1. [4 1 Mar. 2%, 11972 541 DOOR LATCH ASSEMBLY WITH 2,700,290 1/1955 Dall ..70/13s PUSHBUTTON ACTUATIION 2,803,480 8/1957 Foster ...292/216 i 2,881,021 4/1959 Jacobson. ...292/229 [72] Odend Harry 3,044,287 7/1962 Pelcin ..70/99 of Hagerstown, Md.

[73] Assignee: Jamison Door Company, Hagerstown, Md. Primary Examiner-Robert L. Wolfe [2221 Filed: g 25, 1969 Aztorney--Cushman, Darby & Cushman [2]] Appl. No.: 852,678 [57] ABSTRACT A door latch assembly is provided with a pushbutton actuation [52] U.S.Cl ..292/216, 292/92,292/210, to release a lever plate from a pawl so that a door can be 292/227, 292/D1G. 37, 292/DIG. 65, 292/DIG. 71, opened by free rotation of the pawl relative to a keeper. The 7 /1 1 7 lever plate is pivotally mounted within a housing which is [51] list. Cl. ..E0 5c 3/26 s red with a base plate to the surface of the door, and the FIE-Id 01 Search "292/92, 93, lever plate is normally urged into latching engagement 292/216, 37; 248/203; 70/229432 the pawl. The pushbutton contacts one end of the lever plate 92 so as to move it out of engagement with the pawl. A separate releasing means, operable from an opposite side of the door [56] References C'ted from the position of the pushbutton means, contacts an op- UNITED STATES PATENTS posite end of the lever plate so as to release the lever plate I from the pawl wlthout affectmg the posltlon of the pushbutton 443,298 1391 Lecelllfl-m means. Thus, it is possible to release the door from the inside 1,287,973 12/1918 Grub --292/170 ofa room even if the pushbutton means has been locked in a 1,844,557 2/1932 Bobrick .248/203 X fi d position 1,919,328 7/1933 Hansen ..292/218 2,655,395 /1953 Groeger ..292/92 9 Claims, 6 Drawing Figures 22 /6 4\ f r:- V77777777771/ i=/ 4g Q lllllllkg hfi J M P f \tmlfjflllllll (A I 0 ,E a 38 2 /8 ,99 f1. 29 1 pl; 1\ 6 1 32 VII-I- fz 36 42 5 W 86 k AAA\ \-'n\\ /d PATENTEBMAR28 m2 3,652,113

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DOOR LATCH ASSEMBLY WITI-I PUSHBUTTON ACTUATION BACKGROUND AND BRIEF DESCRIPTION OF INVENTION This invention relates to an improved door latch assembly for use in latching and locking a door relative to a doorway. More specifically, the invention is concerned with a door latch assembly which can be latched and locked from one side of a door and released from an opposite side of the door.

It is known in this art to provide various types of latching devices which can be secured to a portion of a door for engaging a keeper, or similar structure, carried on the frame or wall I adjacent to the door. Such assemblies have considered various arrangements for causing the door to be latched and fixed in its position once it is closed, and provisions have been made for locking the assembly to prevent an opening of the door from its closed position. Also, it is known in this art to provide for structures which allow for a release of a locked door from inside of a room, such as a refrigeration room or storage area. The capability of releasing a locked door from within a room is important where there is a possibility of accidental locking of a door while an individual is within a room sealed by the door. Representative structures of the general type contemplated by this invention are shown in U.S. Pat. Nos. 219,485; 435,109; 1,676,515; 2,012,732; 2,163,957; 2,464,178; 2,655,395; 2,893,772; 3,149,867; and 3,223,441.

In accordance with the present invention, an improved assembly is provided for latching and locking a door from one side while permitting a release of the door from an opposite side. The improved assembly is tamper proof because it is fastened to the surface of a door with fastening devices that are fully concealed. In addition, the simplicity of its design and structure provide for a very strong assembly which is easily manufactured at a reasonable cost.

The improved door latch assembly is provided with a pushbutton for releasing the assembly from a latched condition. The pushbutton is actuated with very little force because no linkages or other connecting devices are moved by the pushbutton to cause an unlatching of the door. Instead, the pushbutton merely operates a lever plate which is easily moved out of engagement with a pawl means so as to completely release the pawl means for free rotation about an axis. When the door is closed to a latched position, the lever plate is normally urged back into engagement with the pawl means, and the pawl means fixes the position of the door relative to a keeper secured to an adjacent frame or wall. A separate releasing mechanism is provided from an opposite side of the door and functions to move the lever plate out of engagement relative to the pawl means without requiring any movement of the pushbutton. Thus, the pushbutton can be provided with a locking device, such as a padlock, to prevent its actuation from one side of the door, and the door still can be released from an opposite side by the separate releasing means.

The constructional features of the door latch assembly of this invention include a base plate and a housing which are secured together in such a way that they cannot be disassembled once the door latch is in place on the surface of a door. The base plate is attached to a surface of a door without any requirement for reconstructing the door itself, and attachment is made with concealed fastening devices. A lever plate is mounted for rocking movement about a fixed pivotal axis within the housing, and a pawl means is also mounted for rocking movement about a fixed axis relative to the housing. The pawl means includes a latching end portion, which extends out of an open end of the housing, together with a locking shoulder which can be engaged by one end of the lever plate to prevent rocking movement of the pawl means in one rotational direction about its axis. First spring means are provided for normally urging the lever plate in a direction which tends to maintain one end of the lever plate in contact with the locking shoulder of the pawl means, and a second spring means is positioned to normally urge the pawl means in a rotational direction which assists in maintaining a locked relationship between the lever plate and the pawl means. A pushbutton is mounted through the housing for movement towards and away from the lever plate so that when the pushbutton is pushed towards the door the lever plate is moved out of locking engagement with the pawl means. This permits free rocking rotation of the pawl means about its axis, and the door can be opened by merely pulling it outwardly away from the doorway which is being closed or sealed. Outward movement of the door allows the pawl means to rotate into an unlatched position relative to the keeper. Finally, there is provided a releasing means which is mounted through the door and through the base plate so as to engage the lever plate in such a way that the lever plate can be moved out of engagement with the pawl without moving the pushbutton. The pawl may be mounted on a vertically disposed rod or shaft which extends all the way through the housing and which can be connected to one or more additional pawls in separate latches. In this way, locking of a main latching assembly will maintain separate pawls of much simpler assemblies in locking engagement.

The latching assembly of this invention is useful for various types of doors. For example, it is especially useful for refrigerator room doors or relatively large doors of storerooms which must be latched and locked to close off one area from adjoining areas. It is important to provide for a release of such doors in the event that an individual becomes locked into a room by accident, and it is likewise important to provide for a strong structure which prevents tampering and disassembly of the mechanism from outside of the room or area which is being sealed or protected.

These and other advantages of the present invention will become apparent in the more detailed discussion which follows, and in that discussion reference will be made to the accompanying drawings as briefly described below.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view, taken on a horizontal plane, of one embodiment of structure for the latching assembly of the present invention, as installed on a door;

FIG. 2 is a side elevational view of the assembly of FIG. 1;

FIG. 3 is a view similar to FIG. 1, showing a second embodiment of structure for the assembly of this invention;

FIG. 4 is an elevational view, corresponding to the position shown in FIG. 2, of a base plate element for the assembly;

FIG. 5 is an elevational view of a typical installation which includes a main latching assembly, which can be locked, and two separate latching assemblies of simpler construction than the main assembly; and

FIG. 6 is a crosssectional view, similar to the view of FIG. 1, showing the simpler construction of additional latching assemblies which may be used with the main latching assembly of this invention.

DETAILED DESCRIPTION OF INVENTION FIGS. 1 and 2 illustrate a first embodiment of the door latch assembly of this invention. As shown in FIG. 1, the entire assembly can be mounted on door and wall surfaces without any requirement for mortising or reconstruction of a door or wall. A door 10 is shown in a closed position relative to a doorway 12. Of course, the door can be mounted in a number of ways in accordance with well known installation techniques, and the door may be sealed relative to the frame or wall portion around the doorway, as would be required for an installation in a refrigerated room.

The assembly of FIGS. 1 and 2 is made up of relatively few components which are easily manufactured and assembled and which offer an extremely rugged construction for doors which must be securely locked. The door latch assembly includes a base plate 14 (further illustrated in FIG. 4) and a housing 16. The base plate is secured to the housing in such a way that essential securing elements are concealed from view and from access once the assembly is installed on the surface of a door. Typical securing arrangements will be discussed with reference to the second embodiment illustrated in FIG. 3. Several working elements are contained within the housing 16 and include a lever plate 18, a pawl means 20, and a pushbutton 22.

The lever plate 18 is in the form of a plate or similar member which can be mounted on a fixed, vertical axis shaft 24 for rocking movement about the vertically disposed axis. The pawl means is formed to have a latching end 26 extending through an open end of the housing 16 and a locking shoulder 28 contained within the housing for engaging a first end 29 of the lever plate 18. The pawl means is mounted on a shaft or rod 30 for rocking rotational movements about a fixed, vertical axis. In the illustrated position, the pawl means is in a latching position for engaging a keeper 32, and the lever plate 18 is in a position to maintain the pawl means and the door in a closed, latched position. A first spring means 34 is positioned to normally urge the lever plate in a direction of rotational movement which will cause the first end 29 of the lever plate to engage the shoulder 28 of the pawl. In a similar fashion, the pawl means 20 is urged into such engagement by a second spring means 36. A bore 38 is formed through the lever plate 18 so that the second spring means 36 can extend between a shoulder 40 of the pawl and a portion of the base plate 14. It can be seen that the base plate 14 is provided with a raised dimple 42 for fixing the position of the second spring means 36, and a similar dimple or projection 44 is provided on the shoulder 40 of the pawl means.

The pushbutton 22, of the FIG. 1 embodiment, is mounted to extend through a bore 46 in the housing 16. A reduced diameter portion of the pushbutton 22 extends outwardly from the housing, and a larger diameter portion 48 remains within the confines of the housing. The larger diameter portion 48 is ofa sufficient size to limit outward movement of the pushbutton 22 through the bore 46. A third spring means, which is illustrated as being in the form ofa leaf spring 50, is positioned to normally urge the pushbutton 22 outwardly from the housing. It can be seen that the third spring 50 is riveted to the lever plate 18 and is normally flexed to maintain the pushbutton 22 out of engagement with the lever plate 18. The keeper 32 is secured to the door frame, or adjacent wall, by any suitable fastening device 52. The fastening device 52 can be placed in a position so that it is inaccessible and concealed once the assembly is installed and the door is latched. A transverse bore 54 is provided through the pushbutton 22 to receive a locking device to prevent inward movement of the pushbutton means. A padlock or similar arrangement can be inserted through the bore 54 so as to bear against outer surface portions of the housing and to prevent movement of the pushbutton means inwardly.

In operating the assembly shown in FIG. 1, it is only necessary to press the pushbutton means 22 with sufficient force to overcome the spring 50 so that the inner end of the pushbutton means 22 can contact the lever plate 18. Continued movement of the pushbutton means 22 causes the lever plate 18 to overcome the spring 34 and to rock about its pivotal mounting 24. Then, the first end of the lever plate is dislodged from engagement with the shoulder 28 of the pawl means 20. At this point, the pawl means 20 is free to rotate about its fixed axis, and thus, the door can be opened by merely pulling it outwardly so as to rotate the pawl means 20 in a counterclockwise direction (as viewed in FIG. 1). A handle 56 may be formed into the housing structure 16 so that the door can be opened by pulling on the handle 56.

It can be appreciated that the operation of the latching assembly, as just described, is very simple with few moving parts and linkages. Movement of the pushbutton 22 is accomplished with very little force inasmuch as the pushbutton merely dislodges the lever plate 18 and does not actuate any separate linkages for moving the pawl means 20. The pawl means 20 rotates freely once the lever plate 18 is out of engagement with its shoulder 28, and no linkages or similar arrangements are required to actuate the unlatching of the pawl means from the keeper 32.

FIG. 2 illustrates an outside view of the assembly. The housing 16 and the keeper 32 may be provided with openings 58 for receiving additional mounting screws. Such additional mounting screws function to correctly align the housing with the keeper once final adjustment is made. However, the basic mounting screws and bolts for the assembly are concealed from view when the assembly is installed.

The embodiment of FIG. 3 represents a slightly different construction for the latching assembly of this invention, but it can be seen that the concepts and principles involved are fully equivalent to what has been discussed for the FIG. 1 embodiment. The following discussion will also describe certain details which were not included in the FIG. 1 discussion, and it is to be understood that the FIG. 1 assembly may be constructed and assembled in accordance with any of the additional information provided below.

The FIG. 3 embodiment includes the same basic elements and relationships as discussed for FIG. 1. A base plate 14 is secured to a housing 16 by screws 62 which are concealed from view and access once the assembly is installed on a door. The housing 16 may be cast or formed in any well known manner so as to generally define a strong casing structure which can contain all working elements of the assembly within a hollow area of the housing. One end of the housing is provided with an opening so that the latching end 26 of the pawl means 20 can project outwardly from the housing and engage a portion of a keeper 32. Threaded borings are provided in solid portions of the housing to receive the screws 62, and thus, the base plate 14 can be secured to the housing once all ofthe working elements are in place.

The working elements are assembled into place very easily prior to attachment of the base plate 14 to the housing 16. The lever plate 18 is fixed to a shaft 24, and the shaft 24 is supported by small bearing blocks 64. Recesses 66 are molded into side walls of the housing interior to receive the bearing blocks 64 at each end of the shaft 24, and this permits a very easy assembly of the lever plate 18 into the housing structure. Also, the provision of bearing blocks 64 eliminates any requirement for drilling or boring openings through the housing itself for supporting the shaft 24, and there is no requirement to form the shaft 24 from a finished material which would be exposed to view on the outside surfaces of the housing 16.

The pawl means 20 is supported on a rod or shaft 30 which extends through aligned openings formed through opposite side walls of the housing 16. The pawl means 20 is secured to the shaft in such a way that rotation of the pawl means will cause the shaft to rotate about a fixed axis which is vertically disposed relative to a door. The pawl means 20 is of such a size that the inner side wall surfaces 68 of the housing can function as bearing surfaces for the pawl means.

In the FIG. 3 embodiment, first spring means 34 and second spring means 36 are disposed in alignment with each other on opposite surfaces of the lever plate 18. The lever plate is provided with recesses for receiving and fixing the positions of the two springs, and it can be seen that these springs function in a fully equivalent way to the springs discussed in the FIG. 1 embodiment. In addition, the third spring 50 is shown in the form of a coiled spring which is received into a relatively deep recess fonned into the interior end of the pushbutton 22. The lever plate 18 is provided with a boring so that the spring 50 can pass through the lever plate and bear against the base plate 14.

Once the working components are in place, the base plate 14 can be secured to the housing 16 by the screws 62. Then, the entire assembly can be attached to the surface of the door 10 by a relatively strong screw 70. The screw 70 is received into an elongate slot 72 (see FIG. 4) of the base plate 14. The elongate slot 72 is provided with an enlarged end portion 74 for receiving the head of the screw 70 after the screw 70 has been secured into the surface of the door 10. When the head is received into the enlarged end of the slot 72, the entire assembly can be slid to secure the assembly to the surface door. In this way, the assembly is attached to the door by a completely concealed and inaccessible fastening device which cannot be tampered with and removed. The elongate slot 72 may be arranged so that after the assembly is slid into an attached position relative to a door, it would be impossible to slide the assembly in an opposite direction when the door is in a latched position. The keeper 32 is also secured in such a way that its fastening device 52 is inaccessible once the door is closed. The keeper 32 may be in the form illustrated or it may be of a two piece adjustable construction of the type shown in U.S. Pat. Nos. 3,149,867 and 3,223,441.

In both the FIG. 1 and FIG. 3 embodiments, a separate releasing means 80 is provided for unlatching the door from inside of a room or area which is being secured by the door. This feature, by itself, is known in this art, but it is an important feature to the type of construction presented by the present invention. The separate releasing means 80 comprises a rod 82 with a head portion 84. A bore 86 through the door allows passage of the rod through the door and into the interior of the door latch assembly. A hole 88 is provided in the base plate 14 so that an end of the rod 82 can pass into the housing 16 to contact a second end 89 of the lever plate 18. In the FIG. 1 arrangement, the separate releasing means 80 merely contacts a surface of the lever plate 18 to cause the lever plate to rock about its vertical axis and to dislodge from engagement with the pawl means 20. This movement is accomplished without any movement of the pushbutton 22, and thus, the pushbutton can be locked with a padlock from the outside and the door can be unlatched from the inside. In the FIG. 3 embodiment, the separate releasing means 80 is received into a recess 90 formed into the lever plate 18. Dislodgement of the lever plate from a locking engagement with the pawl means 20 is accomplished by pressing the separate releasing means 80 towards the door.

FIG. 5 illustrates a typical installation wherein the door latch assembly of this invention is shown at a midpoint position on a door and doorway. In addition, two separate latching assemblies 92 of much simpler construction, are shown at upper and lower positions relative to the main assembly. The separate assemblies 92 function to provide additional latching securement and alignment of a relatively large door. As illustrated, the rod or shaft 30, which carries the pawl means 20 of the main latch assembly, extends upwardly and downwardly for a sufficient distance to carry separate pawl means in each of the simpler assemblies 92. Thus, rotation of the main pawl means causes the other two pawl means to rotate an identical amount about an axis which is common to the axis of the main pawl means 20. Also, a locking of the main latch assembly so as to prevent rotation of the main pawl means 20 will prevent rotation of the pawl means carried in the separate latching assemblies 92 because they are fixed to the same rod or shaft 30 as is the main pawl means 20. FIG. 6 illustrates the simplified construction which can be used for the upper and lower assemblies 92, and it can be seen that such a construction is even more economical to produce than the main latch assembly discussed with reference to FIGS. 1 and 3. However, the additional assemblies 92 assist in a secure latching of a door relative to a doorway without a need for separate padlocks or securing devices. The separate pawls 94 contained within each of the separate assemblies 92 are shown as being secured to the extended shaft 30, and a locking of the rotational position of the shaft 30 by the main assembly will prevent a rotation of the separate pawl means 94.

It can be seen that the latching assembly of this invention provides for a very simple and strong construction which is tamper proof and which provides for a safety release from inside of a room. In addition, the structure of the main door latch assembly is such that additional assemblies, of simpler construction, can be simultaneously actuated and locked with the main door latch assembly. The entire construction is made from any suitable metal material, and plastics can be substituted for certain portions of the assembly where desired.

What is claimed is:

1. An improved door latch assembly which is useful for latching and locking a door relative to a doorway and which can be unlatched from one side of the door even when a lock is applied to an opposite side of the door, comprising the combination of:

a base plate which can be attached to a surface of a door,

a housing secured to said base plate by securing means which are concealed when said base plate is attached to the surface of the door,

a lever plate mounted for rocking movement about a fixed pivotal axis which is substantially parallel to a surface of the door, said lever plate being completely enclosed within said housing,

a pawl means mounted for rocking movement about a fixed pivotal axis within said housing, said pawl means having (a) a latching end which extends out of an open end of the housing, and (b) a locking shoulder which can be engaged by a first end of said lever plate to prevent rocking movement of the pawl means in one direction about its pivotal axis,

first spring means for normally urging the lever plate in a direction which will cause the first end of the lever plate to contact the locking shoulder of said pawl means so as to prevent rocking movement of the pawl means in one rotational direction about its fixed pivotal axis, said first spring means extending between a portion of said base plate and a back surface of said lever plate,

a second spring means for normally urging said pawl means in a direction which maintains the locking shoulder of the pawl means in engagement with said first end of the lever plate, said second spring means extending between a front surface of said lever plate and a portion of said pawl means,

a pushbutton means mounted to extend through said hous' ing for movement towards and away from said lever plate, said pushbutton means being positioned to contact said lever plate and to release the end of the lever plate from its engagement with the locking shoulder of the pawl means when the pushbutton means is pushed towards the surface of the door on which the housing and base plate are secured, whereby said pawl is released by merely pressing said pushbutton means,

a keeper means mounted on a wall or door frame adjacent to the position of said housing and base plate so that the latching end of said pawl means engages the keeper means in a latching relationship when the door is in a closed position relative to a doorway, and

a releasing means mounted through the door and said base plate so as to engage a portion of said lever plate, said releasing means being operable from an opposite side of the door from which said housing and base plate are mounted, and said releasing means being positioned to contact said lever plate to move said lever plate out of engagement with said pawl means without moving said pushbutton means.

2. An improved door latch assembly which is useful for latching and locking a door relative to a doorway and which can be unlatched from one side of the door even when a lock is applied to an opposite side of the door, comprising the combination of:

a base plate which can be attached to a surface of a door,

first spring means for normally urging the lever plate in a direction which will cause the first end of the lever plate to contact the locking shoulder of said pawl means so as to prevent rocking movement of the pawl means in one rotational direction about its fixed pivotal axis,

a second spring means for normally urging said pawl means in a direction which maintains the locking shoulder of the pawl means in engagement with said first end of the lever plate,

a pushbutton means mounted to extend through said housing for movement towards and away from said lever plate, said pushbutton means being positioned to contact said lever plate and to release the end of the lever plate from its engagement with the locking shoulder of the pawl means when the pushbutton means is pushed towards the surface of the door on which the housing and base plate are secured, whereby said pawl is released by merely pressing said pushbutton means, said pushbutton means having a bore formed transversely therethrough for receiving a locking device which prevents movement of the push button means towards the lever plate,

a third spring means interposed between said pushbutton means and said lever plate so as to normally urge said pushbutton means outwardly away from said lever plate,

a releasing means mounted through the door and said base plate so as to engage a portion of said lever plate, said releasing means being operable from an opposite side of the door from which said housing and base plate are mounted, and said releasing means being positioned to contact said lever plate to move said lever plate out of engagement with said pawl means without moving said pushbutton meansv 3. The improvement of claim 1 wherein said pushbutton means includes a bore formed transversely therethrough for receiving a locking device which prevents movement of the pushbutton means towards said lever plate.

4. The improvement of claim 1 wherein said base plate includes a slot therethrough which is enlarged at one end so as to receive the head of a fastening element, whereby said base plate and housing can be attached to a flat surface by a fastening means which is concealed and inaccessible once the base plate and housing are attached to the flat surface.

5. The improvement of claim 1 wherein the lever plate is mounted into said housing by a pin means which is secured to the lever plate and which is carried by removable bearing elements fitted into recesses formed into interior surfaces of the housing, whereby no borings through the housing are required for assembling and receiving the pin means.

6. The improvement of claim 1 wherein said releasing means is mounted to contact a second end portion of said lever plate so as to move the second end portion of the lever plate outwardly away from the base plate.

7. The improvement of claim 1 wherein said housing has a fixed handle means formed onto its outer surface.

8. The improvement of claim 1 wherein said pawl means is fixed to a vertically disposed shaft which passes through said housing to permit rocking movement of the pawl means about said pivotal axis.

9. The improvement of claim 1 wherein said vertically disposed shaft extends to at least one additional latching assembly which also includes a pawl means which can be rocked relative to a keeper.

Claims

1. An improved door latch assembly which is useful for latching and locking a door relative to a doorway and which can be unlatched from one side of the door even when a lock is applied to an opposite side of the door, comprising the combination of: a base plate which can be attached to a surface of a door, a housing secured to said base plate by securing means which are concealed when said base plate is attached to the surface of the door, a lever plate mounted for rocking movement about a fixed pivotal axis which is substantially parallel to a surface of the door, said lever plate being completely enclosed within said housing, a pawl means mounted for rocking movement about a fixed pivotal axis within said housing, said pawl means having (a) a latching end which extends out of an open end of the housing, and (b) a locking shoulder which can be engaged by a first end of said lever plate to prevent rocking movement of the pawl means in one direction about its pivotal axis, first spring means for normally urging the lever plate in a direction which will cause the first end of the lever plate to contact the lockIng shoulder of said pawl means so as to prevent rocking movement of the pawl means in one rotational direction about its fixed pivotal axis, said first spring means extending between a portion of said base plate and a back surface of said lever plate, a second spring means for normally urging said pawl means in a direction which maintains the locking shoulder of the pawl means in engagement with said first end of the lever plate, said second spring means extending between a front surface of said lever plate and a portion of said pawl means, a pushbutton means mounted to extend through said housing for movement towards and away from said lever plate, said pushbutton means being positioned to contact said lever plate and to release the end of the lever plate from its engagement with the locking shoulder of the pawl means when the pushbutton means is pushed towards the surface of the door on which the housing and base plate are secured, whereby said pawl is released by merely pressing said pushbutton means, a keeper means mounted on a wall or door frame adjacent to the position of said housing and base plate so that the latching end of said pawl means engages the keeper means in a latching relationship when the door is in a closed position relative to a doorway, and a releasing means mounted through the door and said base plate so as to engage a portion of said lever plate, said releasing means being operable from an opposite side of the door from which said housing and base plate are mounted, and said releasing means being positioned to contact said lever plate to move said lever plate out of engagement with said pawl means without moving said pushbutton means.

2. An improved door latch assembly which is useful for latching and locking a door relative to a doorway and which can be unlatched from one side of the door even when a lock is applied to an opposite side of the door, comprising the combination of: a base plate which can be attached to a surface of a door, a housing secured to said base plate by securing means which are concealed when said base plate is attached to the surface of the door, a lever plate mounted for rocking movement about a fixed pivotal axis which is substantially parallel to a surface of the door, said lever plate being completely enclosed within said housing, a pawl means mounted for rocking movement about a fixed pivotal axis within said housing, said pawl means having (a) a latching end which extends out of an open end of the housing, and (b) a locking shoulder which can be engaged by a first end of said lever plate to prevent rocking movement of the pawl means in one direction about its pivotal axis, first spring means for normally urging the lever plate in a direction which will cause the first end of the lever plate to contact the locking shoulder of said pawl means so as to prevent rocking movement of the pawl means in one rotational direction about its fixed pivotal axis, a second spring means for normally urging said pawl means in a direction which maintains the locking shoulder of the pawl means in engagement with said first end of the lever plate, a pushbutton means mounted to extend through said housing for movement towards and away from said lever plate, said pushbutton means being positioned to contact said lever plate and to release the end of the lever plate from its engagement with the locking shoulder of the pawl means when the pushbutton means is pushed towards the surface of the door on which the housing and base plate are secured, whereby said pawl is released by merely pressing said pushbutton means, said pushbutton means having a bore formed transversely therethrough for receiving a locking device which prevents movement of the push button means towards the lever plate, a third spring means interposed between said pushbutton means and said lever plate so as to normally urge said pushbutton means outwardly away from said lever plate, a keeper means mounteD on a wall or door frame adjacent to the position of said housing and base plate so that the latching end of said pawl means engages the keeper means in a latching relationship when the door is in a closed position relative to a doorway, and a releasing means mounted through the door and said base plate so as to engage a portion of said lever plate, said releasing means being operable from an opposite side of the door from which said housing and base plate are mounted, and said releasing means being positioned to contact said lever plate to move said lever plate out of engagement with said pawl means without moving said pushbutton means.

3. The improvement of claim 1 wherein said pushbutton means includes a bore formed transversely therethrough for receiving a locking device which prevents movement of the pushbutton means towards said lever plate.