Lock fastener

A lock fastener for bags or other receptacles (B) comprises a plug member and a socket member releasably engageable therewith, the plug member having an engaging tongue which is resiliently lockable with the socket member and unlockable therefrom by a means movable toward and away from the plug member and resiliently retractable to its original position upon releasing the plug member 11 from the socket member 12.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a lock-fastener for bags, briefcases or other 
receptacles adapted to be closed by a flap or cover thereon. 
2. Prior Art 
Most conventional lock fasteners basically comprise a female or socket 
member attached to the body of a bag and a male or plug member attached to 
flap and engageable with the socket member to close the flap over the bag. 
Inadvertently applied pressure to this type of lock fastener would 
sometimes cause separation of the plug member from the socket member, 
leading to an opened flap. Conversely, intended pressure to open the bag 
would often fail to unlock the fastener in the case where the bag is flat 
that is; not enough loaded, at might be experienced with lock fasteners of 
the type disclosed in Japanese Laid-Open Utility Model Publication No. 
50-102706. To eliminate or alleviate such malfunctioning of the known 
devices, there have been introduced some improvements such as are taught 
in Japanese Patent Publication No. 61-25382 in which there is shown a lock 
fastener comprising a socket member having a guide chamber, a slide member 
movably supported in the chamber and having a retaining lug, and a plug 
member having an engaging tongue with an aperture dimensioned to receive 
the lug and adapted to move together with the slide member into and out of 
the chamber of the socket member. In this case, both hands of the user are 
required to register the aperture with the lug and thus join the engaging 
tongue with the slide member, which is literally tedious and time 
consuming. Another difficulty is that the engaging tongue can not make its 
way smoothly into and through the guide chamber of the socket member if 
the bag is loaded either too lightly or too heavily. 
SUMMARY OF THE INVENTION 
With the foregoing difficulties of the prior art devices in view, the 
present invention seeks to provide a lock fastener which incorporates 
means for maintaining easy, smooth normal operation of the fastener and 
means for ensuring freedom from unintentional unlocking of the fastener 
against inadvertent external pressure. 
The above and other fastener and advantages of the invention will be better 
understood from the following detailed description taken in conjunction 
with the accompanying drawings, in which lake reference numerals refer to 
like or corresponding parts throughout the several views. 
According to the invention, there is provided a lock fastener which 
comprises a plug member having a resilient engaging tongue flexibly 
movable about a transverse axis defined at one of its ends and a locking 
recess formed at the opposite end, a socket member having a guide chamber 
adapted to receive the engaging tongue, an anchoring bar extending 
transversely through the chamber and engageable with the locking recess to 
lock the plug member relative to the socket member and a pair of spaced 
resilient gripping fingers, and an unlocking means movable toward and away 
from the plug member and having a presser foot having tapering side walls 
engageable between the pair of gripping fingers, the presser foot being 
engageable with the engaging tongue to unlock the plug member from the 
socket member.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings and FIG. 1 in particular, there are shown 
those component parts which constitute a lock fastener 10 embodying the 
invention. The lock fastener 10 essentially comprises a plug member 11 and 
a socket member 12 which respectively constitute a male and a female part 
of the fastener. 
The plug member 11 has a generally rectangular body 13 including a handle 
portion 14 extending upwardly from one end of the body for manipulating 
movement of the plug member 11 toward and away from the socket member 12. 
Extending horizontally forwardly from the opposite end of the plug body 13 
are a pair of tapering side flanges 15, 15 which are joined together by a 
connection bar 16. 
Interposed between the side flanges 15, 15 is an engaging tongue 17 having 
one of its ends connected to formed integrally with an end wall of the 
plug body 13, while the other end adjacent the connecting bar 16 is held 
free such that the tongue 17 can move resiliently pivotally about a 
transverse axis defined at the said one end of the tongue 17. The free end 
of the engaging tongue 17 is thickened to provide a sloped guide surface 
17a and an transversely extending offset locking recess 17b remote from 
the surface 17a for purposes hereafter to be described. 
Designated at 18 is a connecting stud or studs extending downwardly from 
the plug body 13 adjacent to the handle portion 14 and adapted to secure 
the plug member 11 to a flap F of a brief case B (FIG. 9) in a manner well 
known in the art. 
The socket member 12 is substantially in the form of a rectangular casing 
comprising an upper plate 12a, a lower plate 12b and a peripheral flange 
12c which jointly define a guide chamber 12d dimensioned and configured to 
receive the engaging tongue 17 of the plug member 11. An inlet opening 12e 
is formed at one end of the socket member 12 in communication with the 
guide chamber 12d for passing therethrough the engaging tongue 17 into and 
out of the chamber 12d. The lower plate 12b of the socket member 12 is 
slightly forwardly extended to provide a guide porch 12f for facilitating 
the insertion of the engaging tongue 17 through the guide opening 12e into 
the guide chamber 12d. 
The upper plate 12a of the socket member 12 is stamped or otherwise cut out 
to provide a polygonal through-aperture 19 accommodating therein a pair of 
spaced resilient gripping fingers 20, 20 having respective inwardly 
directed nails 21, 21 and further to provide a pair of elongated guide 
slits 22,22 formed on opposite sides of the aperture 19 and extending 
parallel with the gripping fingers 20, 20. An anchoring bar 23 extends 
transversely through the guide chamber 12d between opposite side walls of 
the peripheral flange 12c of the socket member 12 and has an angled. 
anchoring surface 24 disposed adjacent to a transverse line connecting 
respective one ends of the aperture 19 and the slits 22, 22 for relesably 
engaging the engaging tongue 17 of the plug member 11 as shown in FIGS. 2 
and 3. Extending downwardly from the lower plate 12b of the socket member 
12 are a pair of connecting studs 25, 25 with which to secure the socket 
member 12 to a front web W of the brief case B in a manner similar to the 
studs 18 of the plug member 11. Designated at 26 and better shown in FIGS. 
7 and 8 is an unlocking means movable toward and away from the plug member 
11 and comprising a base 27 having a gripping projection 28 formed on its 
upper surface. 
Extending downwardly centrally from the lower surface of the base 27 is a 
presser foot 29 which is releasably engageable through he aperture 19 of 
the socket member 12 with the engaging tongue 17 of the plug member 11 to 
lock the latter relative to the socket member 12 and which tapers off 
along its lateral side walls 29' toward the inlet opening 12e of the 
socket member 12 as better shown in FIG. 8. 
At opposite side of the presser foot 29 are formed a pair of guide rails 
30, 30 slidingly movable in and along the corresponding guide slits 22, 22 
of the socket member 12. 
The operation of the lock fastener 10 thus constructed will now be 
described with reference to FIGS. 2 through 6 inclusive. 
Coupling of the plug member 11 with the socket member 12 is accomplished by 
inserting the engaging tongue 17 through the inlet opening 12e into the 
chamber 12d of the socket member 12, in which instance the tongue 17 
initially bends down flexibly in contact with the anchoring bar 23 and 
then bounces back up when it is anchored in place with its locking recess 
17b brought into abutting engagement with the angled anchoring surface 24 
as shown in FIG. 2 corresponding to FIG. 5 which illustrates the relation 
between the unlocking means 26 and the socket member 12 when the latter is 
fully engaged with the plug member 11. 
Now, uncoupling or separation of the plug member 11 from the socket member 
12 is accomplished by moving the unlocking means 26 with its gripping 
projection 28 towards the plug member 11, in which instance the presser 
foot 29 intrudes between and spreads the pair of the gripping fingers 20, 
20 outwardly apart from each other while the guide rails 30, 30 slide 
along the guide slits 22, 22 until the presser foot 29 rides over the 
sloped surface 17a of the engaging tongue 17 and reaches near the top end 
of the latter, urging the tongue 17 to move downwardly or sink resiliently 
end thus releasing the anchoring bar 23 from the locking recess 17b as 
shown in FIGS. 3 and 6. In this position of the lock fastener 10, the plug 
member 11 is ready to be pulled out and separated from the socket member 
as illustrated in FIG. 4. Simultaneously as the plug member 11 is thus 
separated, the unlocking means 26 is automatically pushed back into the 
original retracted position shown in FIGS. 2 and 5 by means of a resilient 
action imparted to the presser foot 29 by the gripping fingers 20, 20 as 
the latter slide down the tapering side walls 29' of the presser foot 29 
to restore their original parallel relative position shown in FIG. 3. 
Obviously, various modifications and variations of the present invention 
are possible in the light of the above teaching. It is therefore to be 
understood that within the scope of the appended claims the invention may 
be practiced otherwise than are specifically described.