US3529371A - Latching mechanism for plastic desk calendar stand - Google Patents

Description

Sept. 22, 1970 H. MOORE I 3,529,371

LATCHING MECHANISM FOR PLASTIC DESK CALENDAR STAND Filed Oct. 1:5 1969 FIGI I l H62 HOWARD L. MOORE BY mow United States Patent 3,529,371 LATCHIN G MECHANISM FOR PLASTIC DESK CALENDAR STAND Howard L. Moore, Cochranton, Pa. 16314 Filed Oct. 13, 1969, Ser. No. 865,898

Int. Cl. G09d US. Cl. 40-120 4 Claims ABSTRACT OF THE DISCLOSURE FIELD OF INVENTION Card, pictures and sign exhibiting stands.

PRIOR ART Davidson 3,186,574 and desk calendar stands discussed hereinafter.

OBJECTS With the advent of plastics, such as the polypropylene which are easily molded, and in which a living hinge can be readily formed by thinning out the plastic along a hinge line, several desk calendars formed of this material have appeared. Usually, such calendars are shipped in a flattened condition in which a base portion and a back portion are co-pl'anar. In use, the back portion is pivoted up along a hinge line, and some sort of latch is used to hold the back erect. The problem solved by this invention relates to the latch. Since the plastic elements which constitute these devices are usually thin and springy, most latches are infirm, so that if the calendar stand is accidently bumped or brushed aside, the latch disengages; alternatively, if they rely upon less flexible elements, they are too stiff for easy working. The object now is to provide a latch which will take advantage of the springiness of the plastic to ensure easy engagement of the latching parts, while nevertheless providing secure holding against unintentional disengagement. These and other objects will be apparent from the following specification and drawings, in which:

FIG. 1 is a plan view of the desk calendar support flat condition;

FIG. 2 is a side elevation of the desk calendar support as shown in FIG. 1;

FIG. 3 is a fragmentary cross-section along the line 3-3 of FIG. 1 showing the parts of the locking mechanism disengaged;

FIG. 4 is a side elevation of the desk calendar in erected condition;

FIG. 5 is a fragmentary cross section similar to FIG. 1, but showing the parts of the locking mechanism at the start of engagement, as the back plate is being erected;

FIG. 6 is a fragmentary cross section similar to FIG. 5, but showing the parts of the locking mechanism during an intermediate phase of engagement;

FIG. 7 is a fragmentary bottom plan view of the locking mechanism as seen in the phase of engagement shown in FIG. 6; and,

FIG. 8 is a fragmentary cross section similar to FIGS. 5 and 6, but showing the locking mechanism in fully engaged position, wherein the back plate is erected as in FIG. 4.

Referring now to the drawings, in which like reference numerals denote similar elements, the calendar stand 2 is formed of one piece of molded plastic, preferably polypropylene, and comprises a base 4 and a back 6 connected by a living hinge" 8, i.e., thinnedout portions 8a, 8b, 8c, 8d along a hinge axis. The base is provided with ledges 10, 10a for holding down a calendar (not shown), and the back has a panel 12 upon which a suitable advertising message may be placed or imprinted. Tongues 14, which are struck from base 4 and which are integral with back 6 and which extend across the hinge axis, are provided for propping the base in inclined position (FIG. 4) when back 6 is erected.

The latch with which the invention is primarily concerned includes a generally flat tongue 18 which extends rearwardly from the central portion of base 4, near the free end of which tongue is a hook-like ridge 20 and on the end of which is a wedge-shaped nose 22. The free end of tongue 18 and ridge 20 are parallel to the hinge axis. On back 12 and generally opposite tongue 18 is a ledge 24 and a strap 26 defining therebetween a slot 28. Ledge 24 is offset from and parallel to the hinge axis. A projection 30 along the central portion of strap 26 narrows the slot so that ordinarily its width is less than the thickness of the free end portion, including the ridge 20, of tongue 18.

When the calendar stand is shipped, it is normally flatas shown in FIGS. 1 and 2. When it is in normal use, the back is erected as shown in FIGS. 4 and 8. FIGS. 5-8 illustrate the latching as back 4 approaches erection. As shown in FIG. 5, the lower inclined surface of wedgeshaped nose 22 has engaged projection 30 on strap 26, and the upper inclined surface of nose 22 is about to engage the edge of ledge 24 so thatthe free end of tongue 18 is about to spread strap 26 away from ledge 24. As back 6 swings further upwardly, the lower surface of wedge-shaped nose 22 is forced against projection 30 so as to push the strap aside. FIG. 7 shows with some exaggeration the displacement of strap 26. When the back has swung upwardly sufficiently, ridge 20 snaps in behind ledge 24. In FIG. 8 it will be apparent that, what with strap 26 engaging the side of tongue 18 opposite ridge 20, the latter is trapped behind ledge 24, and it cannot become unhooked unless sufficient force is applied to bend tongue 18, strap 26, and the material at ledge 24. Thus back 6 is securely latched in erected condition.

I claim: 1. A one-piece plastic desk calendar stand, comprising: a base plate, a back plate integrally joined to the base plate along a living hinge axis,

said base and back plates being pivotal relative to one another along said hinge axis between a flat condition in which said plates are substantially coplanar and an erected condition in which said plates are disposed at an angle to one another, and

latch means for holding said plates in erected condition, comprising,

a generally flat tongue on one of said plates,

said tongue having a free edge portion terminating in a free edge disposed towards the other of said plates and parallel to the hinge axis, and

a ridge extending parallel to the hinge axis across said free edge portion adjacent said free edge,

the other of said plates having a ledge having a free edge disposed towards and parallel to the hinge axis and offset therefrom away from said hinge axis and so disposed with respect to said tongue as to swing about an arc, the radius of which pivots around said hinge axis, which intersects the ridge on said tongue when said plates are pivoted from said flat condition to said erected condition, whereby, as said plates are pivoted to erected condition, said ledge engages the ridge and flexes the tongue to permit said ridge to snap behind said ledge and thereby retain said plates in erected condition. 2. A one-piece desk calendar stand as claimed in claim 1, the free end portion of said tongue being wedge-shaped. 3. A one-piece desk calendar stand as claimed in claim 2,

said other plate having thereon a strap having opposite ends integral therewith, said strap being parallel to and spaced from said ledge so as to'define there- 7 between a slot through which the free end portion of said'tongue and the ridge thereon pass when said plates are pivoted to said erected condition, and a projection on an intermediate portion of said strap, said projection extending into said slot and the distance between the projection and the ledge being less than the thickness of the tongue adjal .54 I 1 1 condition towards s'aid flat condition, said strap must be similarly displaced, 7 4. A one-piece desk calendar as claimed in claim 1, said one plate being the baseplate and said other plate being the back plate, said back plate having thereon a spaced pair of tongues extending across said hinge axis and being accommodated and recessed insaid baseplate when said plates are in fiat condition, whereby when said plates are pivoted to erected condition, thelast-named tongues swing downwardly to constitute props for supporting said base plate inclined relative to a'supporting surface.

References Cited 7 UNITED-STATES PATENTS 3,186,574 6/1965 Saxe a -,40 -120 7 3,208,171 9/1965 Davidson...

EUGENE R. CAPOZ IO, Primary Examiner I, H. WOLFF, Assistant Examiner US. Cl. X.R.

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