US2672181A

US2672181A - Convertible furniture construction set

Info

Publication number: US2672181A
Application number: US57446A
Authority: US
Inventors: Walter E Rose
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-10-30
Filing date: 1948-10-30
Publication date: 1954-03-16
Anticipated expiration: 1971-03-16

Description

March 1954 w. E. ROSE ,1

CONVERTIBLE FURNITURE CONSTRUCTION SET Filed Oct. 50, 1948 2 Sheets-Sheet 1 March 16, 1954 w, ROSE 2,672,181

CONVERTIBLE FURNITURE CONSTRUCTION SET Filed 001;. 30, 1948 2 Sheets-Sheet 2 IN VEN TOR.

BY $4 yw 9 97,

Patented Mar. 16, 1954 CONVERTIBLE FURNITURE CONSTRUCTION SET Walter E. Rose, La Grange, Ill.

Application October 30, 1948, Serial No. 57,446

14 Claims.

The present invention relates to knock-down furniture and has special reference to an article of furniture which may be quickly and easily assembled and reassembled in various arrangements of the individual elements to form a number of different pieces of furniture.

More particularly, this invention relates to a plurality of elements constituting a furniture construction set or unit which may be assembled into any one of a number of pieces of juvenile or toy furniture, and, when thus assembled, may be taken apart and reassembled into any other of said pieces of furniture.

The construction unit embodying the present invention preferably comprises four rigid pieces and a flexible fabric member, all having provision for being detachably connected together. These five pieces may be assembled to form a bassinet, a diaper-change rest, a bungle'board, a desk, or an infants seat. The seat is so arranged that, if desired, it may be solidly placed upon an ordinary chair to serve as a high chair.

This construction set or unit is particularly useful where space is limited, as it may take the place of a number of standard pieces of nursery furniture, such as a bassinet, a diaper-change rest, a seat, or a. desk.

Ordinarily, a bassinet is required for only a few months and is then discarded as being of no further use. However, the present set may be employed to form a number of articles of furniture in addition to a bassinet which are useful after the baby has outgrown the bassinet.

For a long period of time, both while a bassinet is used and thereafter, a diaper-change rest or table is quite essential. During the period that the present unit is also used for a bassinet, it may be changed from a bassinet to a diaper-change table and back again merely by unsnapping a few snaps at one end of the flexible member and then resnapping them in a new location. The unit may be changed from a diaper-change table to a seat with almost equal ease, and also assembled to form a bungle board or a desk. As a desk the unit will be useful for a number of years. Thus, a single furniture construction unit embodying the present invention may be employed in place of a whole suite of juvenile furniture.

It is therefore an object of this invention to provide a furniture construction set of relatively few pieces which may be readily assembled and reassembled into any one of a number of pieces of juvenile furniture.

The present construction unit also has the advantage that it may be easily transported. When sired articles of furniture.

It is therefore another object of the present invention to provide a furniture construction set which when knocked down will form a small, compact bundle that may be easily transported.

A further object of the invention is to provide such a furniture unit which may be assembled to form various articles of furniture which will be strong and rigid.

A still further object is to provide such a construction unit having a small number of easily formed elements.

when considered with the drawings, in which:

Fig. 1 is a perspective view of a seat assembled from a construction unit embodying the present invention;

Fig. 2 is a top plan view of the seat illustrated in Fig. 1;

Fig. 3 is a front elevational view of the seat; Fig. 4 is a side elevational view thereof;

bodying the present invention;

Fig. 6 is a perspective view of a bungle board formed from the present construction set;

from the present construction set;

Fig. 8 is a perspective view of a babys diaperchange table formed from the present construction set;

struction set; and

Fig. 10 is a perspective view of the various elements of the set arranged in a compact package for being transported or stored. 45

55 ployed.

Further objects and advantages will be apparent from the following description and claims Fig. 5 is an exploded view of the various elements going to make up a construction unit em- Fig. '7 is a perspective view of a bassinet formed Fig. 9 is a desk formed from the present con- Referring to the drawings, and more particularly to Fig. 5 thereof, there is shown a construction set embodying the present invention which comprises a pair of side elements I I and I2, a pair of connecting or bridging elements I3 and I4, and a flexible fabric member I5. The side elements I I and I2 and the bridging elements I3 and I4 may be formed of any strong, substantially rigid material, such as wood, plywood, or a plastic, although any other suitable material may be em- The side elements H and [2, which serve to form the sides of the articles of furniture, are similar. Their longitudinal edges are preferably of different lengths. Those which, for convenience, may be termed the rear edges, are longer and extend above or beyond the opposite or front edges as illustrated. Each of the side elements is provided with a slot it extending horizontally inwardly from the rear edge adjacent the lower ends thereof when the sides are in upright position, to a depth greater than one half the width of elements H and If as shown in Figs. 1, 4;, 5, 7, and 9. Each of the side elements is also provided with a pair of similarly positioned slots adjacent the upper portion of the opposite or front edge thereof. One of these slots IT extends inwardly substantially normal to the longitudinal axis of the side element to a depth greater than one-half the width of elements H and i2 and preferably substantially parallel to the slots l6, while the other slot ii; of the pair preferably slants inwardly and down- Wardly. To permit access to both these slotsthe upper front edge of the side elements is cut back at Isa.

Inwardly extending slots intended for cooperation with the various slots in the respective side elements are provided adjacent the ends of the bridging elements l3 and I l. The bridging element 13 has slots l9 and 29 which extend inwardly from one of the edges substantially normal to the longitudinal axis of this member to a depth less than one-half the width of element l3. Ihe other bridging element, M, has

slots

25 and 22 also extending inwardly from a longitudinal edge thereof adjacent its opposite ends to a depth less than one-half the width of element The portions of this bridging element i l on the outer sides of these slots are preferably shortened, providing notched corners 23 at each end. Extending inwardly from the same edge as the slots 2! and 22 there is a large, central, cut-out portion 22a.

The fifth element or piece of the construction unit consists of the flexible fabric member l5.

It may be of any suitable material having sufficient strength, such, for example, as canvas. The fabric member I5 is substantially equal in width to the distance between the notches i9 and 28 or 21 and 22 of the bridging elements, .i

tioned in the notches lit, for being secured to the lower side thereof. A transverse securing flap 28 is. provided at the end opposite to. that having the side flaps 2t and 25. Spaced a short distance from the flap 2% is a pair of preferably oval, leg-receiving openings fl. which are preferably reinforced, are centrally located and extend transversely of the fabric member.

Securing means are provided for attaching the flexible fabric member 55 to the side elements H and i2, and the bridging elements l3 and It. While various types of fastening members. may be used, ordinary snap fasteners comprising a ball member and a socket member havev proved satisfactory. Socket members 2% are secured. on

These holes,

-l the

flaps

24, 25, and 26 of the fabric member l5. The ball portions 29 are arranged on each of the side elements and bridging elements in the construction illustrated. Three ball portions 29 are provided on the outer faces of the upper end portions of each of the side elements. A pair of ball members 353 is secured on the bottom face of the bridging member l3 and seven ball members 3| are secured on one face of the bridging member M. Five of the ball members 3! are adjacent a longitudinal edge and a ball member is positioned at each end of this bridging element. The number and arrangement of the snaps may be varied.

A number of different articles of juvenile furniture may be constructed from these various elements hereinabove described. Referring to Figs. ll, a childs seat is there illustrated. To assemble this seat the two side elements II and I? are arranged in opposed relationship with their longitudinal axes extending vertically. The bridging element is connected to the bottom ends of these side elements by being moved to slide the slots IS and iii of the bridging element into the cooperating slots iii in the lower ends of the side elements. The cooperating slots form detachable joints for holding the parts in assembled relation. The bridging element I is next secured to the upper end portions of the side elements by being moved to slide the slots 2i and 22 into the cooperating slots 5? in the upper end portions of the side elements. This places the cut-out portion 22a inwardly or to ward the rear, as shown particularly in Figs. 1 and 2.

Thereafter the canvas member is secured in place by snapping the socket members 28 of the side flaps 2t and 25 over the ball portions 2% on the outer faces of the side elements. One end of the fabric member is thereby secured to the upper end portions of the two side. elements. The opposite end of the fabric member is extended downwardly below the bridging member l4 and then forwardly thereunder to permit the socket members 28 on the flap- 23 to be connected to the ball members 3| adjacent the outer longitudinal edge of the bridging element it.

If desired, the bridging elements l3 and i4 may be provided on their lower faces with projecting

members

32 and 33, respectively. These projecting members have flat surfaces at one end positioned to tightly abut the adjacent face of the side elements Ii and 12 when assembled. This serves to further rigidify the resulting furniture construction.

With a seat assembled as shown in Figs. 1 to l, a child may be supported on the flexible fabric member while sitting within the cut-out portion 22a of the bridging element M, with the legs extending out through the openings 2? at the front ofv the seat. A separate substantially rigid seat portion is preferably placed, upon the fabric member for supporting a child and preeluding pressure against the back of the legs by the portion of the flexible member surrounding the leg holes 2i. If desired, the above de scribed seat assembly may be placedv on an ordinary chair to serve as a high chair for an infant. When the chair. is intended for such use the bridging member i3 is preferably arranged with the projecting members 32 uppermost, thus presenting a flat lower surface.

Due to the fact that the slots [7 in the side elements preferably have a depth greater than one.- half the widthof the side elements, there is substantially no possibility of a child forcing the element I 4 forwardly out of engagement with the slots I! while sitting in the seat.

To change the seat shown in Fig. 1 to a bassinet 'as illustrated in Fig. 7, it is advisable to unsnap socket members 28 on either

flap

24 or 25, remove the bridging element M by sliding it forwardly, and then rotate it substantially about the outer longitudinal edge to which the fabric member is secured upwardly and outwardly somewhat less than 360 and until the slots 2! and 22 in the bridging element are aligned with the downwardly extending slots IS in the side elements II and 12. The bridging element I4 is then replaced between the side elements with the slots 2| and 22 cooperating with the slots l8 as shown in Fig. 7. Thereafter the snaps are refastened as they were. To change the bassinet back to a seat it is only necessary to reverse the steps just described.

The bassinet shown in Fig. [may readily be altered to form a diaper-change table or rest, such as illustrated in Fig. 8. To accomplish this the end of the fabric member is unsnapped from the bridging member l4, and is then pulled along the rear edges of the side members to the lower side of the bridging member l3 to which it is fastened by the snap portions 3d. The ball portions of the snaps on the bridging element 13 are so positioned that the fabric will be stretched tight lengthwise when secured as just described. The width of the fabric member I5 is such that when the socket portions of the snaps 28 on the side flaps 24 and 25 are secured to the outer sides of the side elements, the portion of the fabric therebetween will also be stretched fairly tight.

To form the bungle board as illustrated in Fig. 6 from a diaper-change table, the bridging member I4 is removed and the remaining structure is placed on a support, such as a bed, with the canvas side lowermost. An infant can then be placed in the bungle board with a pillow or other object positioned adjacent the open end, and the baby will be perfectly safe, as the fabric member I5 upon which the baby rests is connected to the side elements II and I2 and the bridging element l3 so is prevented from movement relative thereto. Thus, an infant may be taken visit-- ing and put to bed in the bungle board even when it is too large for the bassinet.

After an infant has outgrown the various articles of furniture heretofore described, the present construction set may be assembled to form a desk or vanity which a child may still use for a number of years. To construct the desk or vanity, the bridging element I3 is secured by the cooperating slots I9, 20 and Il to the upper portions of the side elements H and I2 and the bridging element I 4 is secured by the cooperating slots 2|, 22 and It between the lower portions of the side elements. The cut-out portion 22a. in this arrangement provides leg space for the user. The fabric member is not employed as a part of the desk or vanity, as a general'rule.

When disassembled, the various parts of the present seat may be formed into a compact bundle, as shown in Fig. 10. The side elements are preferably sandwiched between the bridging elements which are arranged with the projecting

portions

32 and 33 extending inwardly. Accordingly, the ball portions of the snaps on the bridging element M are outermost and the ends of the fabric member may be wrapped around the side and bridging elements and snapped to the bridging element [4, as shown in Fig. 10. This results in a very compact bundie which may be easily carried about or stowed away in a small space when being transported or stored.

While the present invention has been described as a construction set or unit for forming articles of juvenile furniture, it may also be used for constructing similar toy articles of furniture. For this purpose the various parts comprising the set will be made much smaller and of lighter materials so that the assembled articles of furniture will be suitable for use with dolls.

The present invention has been described with cooperating slots as the joints for detachably connecting the various elements. However, the invention is not to be limited thereto as other types of joints or connecting arrangements may be employed for detachably connecting the various elements to form sturdy articles of furniture when properly assembled. Instead of the snap fasteners described, other types of fasteners may also be employed for attaching the fabric to the various other parts of the construction set. Additional modifications may also be made.

It is therefore to be understood that various changes and modifications may be made in the present invention without departing from the spirit and scope thereof, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

Having thus described my invention what I claim and desire to secure by Letters Patent is:

l. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of side supporting elements for being arranged in substantially opposed relationship, a bridging element and a flexible fabric member, said elements having cooperating fastening means for detachably connecting an end portion of said bridging element to each of said side elements while the latter are in spaced substantially opposed relationship, and cooperating fastening mean on said fabric and said elements arranged for detachably connecting the sides adjacent one end of said fabric member to said side elements and the opposite end of said member to said bridging element.

2. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of side supporting elements for being arranged in substantially opposed relationship, a pair of bridging elements, a flexible fabric member, cooperating fastening means adjacent the ends of said bridging elements and adjacent the end portions of said side elements for detachably connecting the opposite ends of said bridging elements to said side elements to maintain the latter in spaced substantially opposed relationship, and cooperating fastening means on said fabric and said elements arranged for detachably connecting the sides adjacent one end portion of said fabric member to said side elements and the other end portion of said fabric to at least one of said bridging elements.

3. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a, pair of similar side supporting elements for being arranged in substantially opposed parallel relationship, a pair of bridging elements of substantially the same length, a flexible fabric member, cooperating fas-' tening. means adjacent the ends of said bridg elements and adjacent the end portions of said side elements for detachably connecting the op-- po'siteend portions of said bridging elements to said: side elementsto maintain. the latter in spaced substantially opposed parallel arrangement, and fastening means for detachably connecting the sides: adjacent one end portion of said fabric member to said opposed side elements and the other end portion of said fabric to one of said bridging elements.

' A knock-down furniture construction set consisting of, individual pieces capable of being assembled into any one of a number of'items of furniture, comprising a pair of similar side. supporting elements for being arranged in substantially opposed parallel relationship, a pair of bridging elements of substantially the same length, a flexible fabric member, cooperating fasteni-ng. means adjacent the ends of said bridging elements and adjacent the end portions of said side elements for detachably connecting the 0pposite end portions of said bridging elements to said side elements to maintain the latter in substantially opposed parallel arrangement, said fabric member being of a Width to stretch substantially between said opposed side members and of a length at least about as long as said side members, said fabric and said elements having cooperating fastening, means arranged for detacha-bly connecting the sides adjacent one end portion of said. fabric to said side elements and the other end portion to at least one of said bridging elements.

5.. A knock-down furniture construction set consisting of individual pieces capable of. being assembled into any one of a number of items of juvenile furniture, comprising a pair of similar side supporting elements for being arranged in substantially opposed parallel relationship, a pair of bridging elements of substantially the same length and a, flexible fabric member, cooperating fastening means adjacent the ends of said bridging elements and adjacent the end portions of said side elements for detachably connecting the opposite end portions of said bridging elements to said side elements to maintain the latter in substantially opposed parallel arrangement, said fabric member being of a width to stretch substantially between said opposed side members and of a length at least about as long as said side members and having a pair of centrally located leg; openings adjacent the end intended to be se cured: to said bridging elements, and said fabric and said elements having cooperating fastening means arranged for detachably connecting the sides adjacent one end portion of said fabric to said side elements and the other end portion to at least one of said bridging elements.

6. A knock-down furniture construction set consisting of individual pieces capable'oi, being assembled into any one of a number of items of furniture, comprising a pair of elongated side supporting members for being arranged in substantially opposed relationship with the longitudinal axis thereof extending substantially vertically, a pair of elongated bridging elements, cooperating fastening elements adjacent opposite ends, of one of said bridging elements and adjacent the lower ends of said side elements for detachably connecting said elements together, securing means adjacent corresponding edges of the upper end portions of said side members and securing; means adjacent the opposite ends of: said second bridging member for; cooperating therewith to detachably secure the cooperating bridging member in a downwardly sloping plane, a flexible fabric member, and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric member to the upper end portions of said side elements and the other end portion of said fabric to one of said bridging members.

'7. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of elongated. side supporting members for being arranged in substantially opposed relationship with the longitudinal axis thereof extending substantially vertically, a pair of elongated bridging elements, cooperating fastening means adjacent opposite ends of one of said bridging elements and adjacent the lower ends of said side elements for detachably connecting said elements together, downwardly extending securing means adjacent corresponding edges of the upper end portions of said side members and securing means adjacent the opposite ends of said second bridging member for cooperating therewith to detachably secure said bridging element in a downwardly extending position adjacent one side of the upper end portions of said elements, a flexible fabric member, and cooperating fastening means on said fabric, said side elements and said last bridgi-ng element for detachably connecting one end portion of said fabric to said last bridging member adjacent the upper edge thereof and the opposite edge portion of said fabric member to the far sides of said side elements adjacent their upper ends. for forming a. bassinet.

S. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture comprising a pair of side supporting elements for being arranged vertically in substantially opposed parallel relationship, a pair of bridging elements for being detachably secured to said side elements to hold them in said relationship, each of said side members having a a similarly arranged slot adjacent the lower portion extending inwardly from an edge and a pair of slots in the upper portion, one of said pair of slots extending: inwardly and the other of said pair of slots extending obliquely inwardly and downwardly from an edge of said side elements, said. bridging elements having slots extending in,- wardly from their edges adjacent their opposite ends for cooperating with the pairs of slots in said side members for detachably securing said bridging elements between said side elements, a flexible fabric member and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric to the upper ends of said opposed side elements and the opposite end of said fabric member to either of said bridging elements.

9. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of elongated side supporting members for being arranged in substantially opposed relationship with the longitudinal axis thereof extending substantially vertically, a pair of bridging elements for being detachably secured to said side elements to hold them in opposed position, each of said side mem bers having a similarly arranged slot adjacent the lower portion extending inwardly from an edge substantially normal to the longitudinal axis thereof and a pair of slots in the corresponding edges in the upper portion, one of said pair of slots extending inwardly substantially normal to the longitudinal axis of the side members and the other of said pairs of slots extending downwardly, said bridging elements having slots extending inwardly from their edges substantially normal to their longitudinal axis adjacent their opposite ends for cooperating with the slots in said side members to detachably secure said bridging elements betweensaid side elements, a flexible fabric member, and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric to the upper ends of said opposed side elements and the opposite end of said fabric to one of said bridging elements.

10. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of elongated side supporting members for being arranged in substantially opposed relationship with the longitudinal axis thereof extending substantially vertically, a pair of bridging elements for being detachably secured to said side elements to hold them in opposed position, each of said side members having a similarly arranged slot adjacent the lower portion extending inwardly from an edge substantially normal to the longitudinal axis thereof and a pair of slots in the corresponding edges in the upper portion, one of said slots extending inwardly substantially normal to the longitudinal axis of the side members and the other of said pairs of slots extending downwardly, said bridging elements having slots extend ing inwardly from their edges substantially normal to their longitudinal axis adjacent their 0pposite ends for cooperating with the slots in said side members to detachably secure said bridging elements between said side elements, one of said bridging elements having a relatively large centrally located cut-out portion in one edge thereof of a size to fit about a child, a flexible fabric member, and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric to the upper ends of said opposed side elements and the opposite end of said fabric to one of said bridging elements. I

11 A knock-down furniture construction set connecting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of elongated side supporting members for being arranged in substantially opposed relationship with the longitudinal axis thereof extending substantially vertically, a pair of bridging elements for being detachably secured to said side elements to hold them in opposed position, each of said side members having a similarly arranged slot adjacent the lower portion extending inwardly from an edge substantially normal to the longitudinal axis thereof and a pair of slots in the corresponding edges in the upper portion, one of said slots extending inwardly substantially normal to the longitudinal axis of the side members and the other of said pairs of slots extending downwardly, said bridging elements having slots extending inwardly from their edges substantially normal to their longitudinal axis adjacent their opposite ends for cooperating with the pairs of slots in said side members to detachably secure said bridging elements between said side elements, one of said bridging elements having a relatively large centrally located cut-out portion in one edge thereof of a size to fit about a child, a flexible fabric member and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric to the upper ends of said opposed side elements and the opposite end of said fabric to one of said bridging elements, said fabric member having two centrally located leg-receiving openings adjacent the end for being secured to said bridging elements.

12. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of side supporting elements for being arranged vertically in substantially opposed parallel relationship, a pair of bridging elements for being detachably secured to said side elements to hold them in opposed position, one of said bridging elements having a relatively large centrally located cutout portion in one edge thereof of a size to fit about a child, said side members having similarly arranged slots extending inwardly from an edge adjacent the lower portion and similarly arranged slots extending inwardly from an edge adjacent the upper portion, said upper slots being of a depth greater than one-half the width of said side elements, said bridging elements having slots extending inwardly from their edges for cooperating with the slots in said side members to detachably secure said bridging elements between said side elements, the slots in said cutout bridging element extending inwardly from the same side as said cut-out portion, a flexible fabric member, and cooperating fastening means on said fabric and said elements for detachably connecting the sides adjacent one end portion of said fabric to the upper ends of said opposed side elements and the opposite end of said fabric to one of said bridging elements.

13. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of similar side supporting elements for being arranged in spaced substantially opposed parallel relationship, a pair of bridging elements, a flexible fabric member, cooperating fastening means adjacent the ends of said bridging elements and adjacent the end portions of said side elements for detachably connecting the opposite end portions of said bridging elements to said side elements to maintain the latter in spaced substantially opposed parallel arrangement, and fastening means for detachably connecting the sides adjacent one end portion of said fabric member to said opposed side elements and the other end portion of said fabric to one of said bridging elements, said bridging elements being interchangeable with respect to said side supporting elements.

14. A knock-down furniture construction set consisting of individual pieces capable of being assembled into any one of a number of items of furniture, comprising a pair of similar side supporting elements for being arranged in spaced substantially opposed parallel relationship, a pair of bridging elements, a flexible fabric member, cooperating fastening means adjacent the ends of said bridging elements and adjacent the end portions of said side elements for detachably connecting the opposite end portions of said 1% bridging elements to said side elements to main-.- tain the latter in spaced substantially opposed parallel arrangement, and fastening means for detachably connecting the sides adjacent one end portion of said fabric member to said opposed side elements and the other end portion of said fabric to one of said bridging elements, said bridging elements being interchangeable with respect to said side supporting elements, and said fabric member having two centrally located leg-receiving openings adjacent the end for being secured to said bridging elements.

WALTER E. ROSE.

References Cited in the file of this patent UNITED STATES PATENTS Number Number 15 Number Name Date Eger May 19, 1925 McGlothern Oct. 11,, 1927 Burton Nov. 19, 1929 Jenny Feb. 18, 1930 Kling Nov. 1, 1932 Morse Nov. 6, 1934 Hansburg June 8, 1939 Rosenthal Jan. 2, 1945 Puls May 14, 1946 Seitz Apr. 8,, 1947 Silverman Aug. 16, 1949 FOREIGN PATENTS Country Date Great Britain July 5, 1932