Floor protector mat for desk chair

3,333,805

Aug. 1, 1967

W. O- MARSHALL

FLOOR PROTECTOR MAT FOR DESK CHAIR

Filed June 4, 1965

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3,333,805

Patented Aug. 1, 1967

United States Patent Office

3,333,805

FLOOR PROTECTOR MAT FOR DESK CHAIR William Cochran Marshall, 5323 Flint, Shawnee, Kans. 66203 Filed June 4, 1965, Ser. No. 461,279

Claims. (CI. 248—188.9)

This invention relates to improvements in a combination desk chair support and carpet protector and, more particularly, to a mat assembly of the type which protects the carpet from wear by the user’s shoes and chair casters, provides a smooth rolling surface for the chair, and which is constructed in a novel manner to preclude shifting of the mat on the carpet during normal use of the chair.

It is well known to use a sheet of generally rigid material over office carpeting adjacent the knee well of a desk to provide a surface support for an office chair or the like so that not only will the carpet itself be protected from wear due to movements of the user’s feet and the chair casters thereover, but also the sheet provides a smooth, hard surface to facilitate maneuvering of the chair with respect to the desk. Although sheets of this type serve their intended purpose in an efficient manner, they have the inherent defect in that the bottom surface of the sheet does not present sufficient frictional engagement with the carpeting to prevent lateral shifting of the sheet in different directions when horizontal forces or horizontal components of inclined forces are applied thereto. For instance, walking on such sheets oftentimes causes sufficient forces to be applied to the upper surface of the sheet in a direction generally parallel or at a slight angle with respect to the plane of the sheet to cause the latter to be shifted relative to the carpet. Furthermore, in the normal movement of a person seated at the desk, his feet frequently are resting on the carpeting beyond the confines of the protective sheet and therefore, when he pushes against the chair to shift it relative to the desk and using his feet as a brace, forces are applied to the mat which also tend to shift it relative to the desk. A series of these movements results in the sheet being displaced from its desired position and thereby requiring repositioning of the same at frequent intervals.

Also, a sheet of the type described has a predetermined thickness which, when the sheet is disposed on a carpet, presents a shoulder or an abutment which can be inadvertently kicked when walking toward the sheet. Such impacts on the edges of the sheet displace the same away from its desired location and periodically necessitate repositioning of the same.

In view of the fact that the sheets have a certain degree of transverse flexibility even though constructed of relatively rigid synthetic resin or wood fiber materials, weight applied to the central portion of the mat by a person seated in a chair thereon often causes the edges of the mat to move up above the level of the carpeting as the central area of the mat is forced down into the carpeting by the weight thereon. Repeated deflection of the type normally can cause permanent bowing of the mat, making undesired deflection thereof even easier and presenting an edge disposed to cause permanent and expensive damage to wooden uprights or legs of desks and consoles adjacent thereto upon shifting of the mat toward the same. Such bowing of synthetic resin mats can even cause sufficient fatigue of the material to eventually result in cracking or breaking of the protective device. Turning the mat over is only a very temporary solution since a permanent set has been forced in the sheet and in a short time it simply bows but in the opposite direction when weight is placed thereon.

Chair mats as discussed above are usually provided with a lip portion on one edge thereof to fit within the knee well of the desk and desirably, such lip is cut to fit as close as possible to the normal rolling surface of the chair caster to prevent rolling the chair off the mat during norma maneuvering of the chair. However, this means that the mat lip and adjacent margins of the mat are frequently located in very close proximity to the desk uprights oi legs. The result is that shifting of the mat to even a small extent relative to the desk can cause damage to the latter as the mat edges ride against and up onto the supporting members of the desk.

The present invention is directed to the elimination oi the problems set forth above with respect to protective sheets of the type described by utilizing structure thereon for preventing lateral movements of the sheet when displacing forces are applied thereto. This is accomplished by the provision of non-slip devices on the underside oi such a sheet wherein each device has a series of projections disposed to penetrate the pile of a carpet so the tendency of the sheet to move laterally is offset by the frictional forces between the projections and the carpet pile. The sheet will thus remain in a stationary position at all times with respect to the desk and adjacent furniture.

It is, therefore, the primary object of this invention to provide a combination chair support and carpet protective assembly including a generally planar sheet adapted to be positioned adjacent the knee well of a desk, of sufficient size to provide a smooth, rolling surface for the chair throughout the normal range of required movement thereof and having frictional devices on the underside thereof capable of precluding lateral displacement of the mat without permanent attachment of the mat to the floor or damage to the carpeting.

Another object of the present invention is the provision of a combination support and carpet protective assembly for an office desk chair wherein the assembly has a plurality of nonslip devices, each having a plurality of generally parallel, downwardly extending projections secured to the underside of a generally rigid, smooth, flat sheet, whereby the projections penetrate the pile of a carpet to an extent when the sheet is disposed thereover to thereby preclude movement of the sheet along the carpet when lateral forces are applied to the sheet.

A further object of this invention is the provision of a carpet protector of the aforesaid character wherein the non-slip devices, in the preferred form, are located adjacent the center of the sheet so that the forces applied to the sheet as an office desk chair is rolled thereon, are carried substantially directly by the nonslip devices to minimize the tendency for the sheet to bow in the center when weight is placed thereon.

Yet another object of the present invention is the provision of an assembly of the type described wherein the projections of the nonslip devices are preferably defined by teeth of generally conical configuration and have rounded, lowermost extremities to prevent matting of the carpeting, to facilitate penetration of the teeth into the pile of the carpet, and to prevent piercing of the back of the carpet during normal usage of the assembly.

In the drawing:

FIGURE 1 is a perspective view of one embodiment of the carpet protector showing the nonslip devices adjacent to the center of the sheet;

FIG. 2 is a view similar to FIG. 1 but illustrating another embodiment of the carpet protector with the nonslip devices thereof adjacent to the periphery of the sheet and adjacent to the center thereof;

FIG. 3 is a bottom plan view of one of the nonslip devices;

FIG. 4 is an enlarged, fragmentary, cross-sectional view of one form of a device illustrating its disposition with a carpet or rug having a relatively thin pile; and

3,333,805

FIG. 5 is a view similar to FIG. 4 but illustrating another form of the device for use with a carpet having a relatively thick pile.

The combination chair support and carpet protective assembly of the first embodiment illustrated in FIG. 1, is denoted by the numeral 10 and includes a polygonal sheet 12 of self-sustaining material having a pair of flat, generally smooth surfaces 14 and 16, surface 14 being the bottom or lower surface of sheet 12 and surface 16 being the upper surface thereof. As illustrated, sheet 12 is especially adapted for use with an office chair adjacent the knee well of a desk and, to this end, generally has a lateral lip 18 integral therewith and adapted to extend beneath a desk into the knee well for protecting a portion of a carpet therewithin.

Sheet 12 is of conventional design and construction and may be formed from methyl methacrylate, a pressed wood material, or a pressed wood mat with high pressure laminated synthetic resin coating sheets on one or both surfaces thereof. The upper surface 16 is smooth to facilitate the movements of chair casters thereover.

A plurality of nonslip devices 20 are secured to lower surface 14 for engagement with the pile of a carpet to prevent lateral movements of sheet 12 with respect to the carpet. Each device 20 includes a disc-shaped base 22 and a plurality of projections or teeth 24, integral with and extending downwardly from base 22. In the form of the device 20 of FIG. 4, the length of each tooth 24 is related to the actual depth of the carpeting pile for which assembly 10 is designed to be used and is of relatively short length.

However, in the form of device 20 illustrated in FIG. 5, each tooth 24 is substantially longer so that the device will be suitable for use with a carpet 32 having a relatively thick pile 34 secured to and extending upwardly from a back 36. In either form of the device 20, the teeth 24 preferably have a generally conical configuration and each tooth is rounded at the bottom extremity 38 thereof to obviate substantial piercing of the pile or the back of the carpet. Thus, the carpet is not in any way damaged or weakened by devices 20. The conical configuration of teeth 24 facilitates the insertion thereof into the pile of the corresponding carpet and minimizes the space occupied by each tooth 24 while providing required structural rigidity therefor.

It is desirable that the teeth 24 be of a length to cause the spherical lower surfaces thereof to terminate short of the back of the corresponding carpet and be supported by the portions of the pile directly adjacent to the upper surface of the corresponding carpet back.

Devices 20 are secured to surface 14 in the dispositions shown in FIG. 1 with teeth 24 projecting downwardly from this surface. Although five devices 20 have been illustrated as being secured to surface 14, it is clear that less than this number can be used so long as there is no tendency for sheet 12 to rotate about a vertical axis when lateral forces are applied to the sheet.

Base 22 of each device 20 is preferably provided with a completed flat, upper face which thereby complementally engages bottom surface 14 throughout the entire upper surface area of base 22. Any suitable means may be provided for connecting each device 20 to sheet 12. Preferably however, bases 22 are bonded to lower surface 14 by the use of a suitable bonding agent.

Each device 20 is preferably molded from a synthetic resin material such as polystyrene or the like. Thus, teeth 24 are integral with base 22. If each device 20 is molded from this material, and if sheet 12 is formed of methyl methacrylate or the like, a suitable solvent such as ethylene dichloride may be utilized as the bonding agent between base 22 of each device 20 and surface 14 of sheet

12. This solvent causes each of the bases 22 to firmly adhere to sheet 12 to provide a positive bond therebetween. If sheet 12 is formed from pressed wood or the like, a suitable epoxy resin may be used as the bonding agent to provide a firm bond between such components. This manner of securing devices 20 to sheet 12 gives a neat and finished appearance to protector 10 and, if sheet 12 is transparent, as it is if constructed of methyl methacrylate, the bonding agent is essentially concealed from view to enhance the over-all appearance of protector 10.

In use, sheet 12, with devices 20 affixed thereto, is laid on a carpet so that the projections of devices 20 penetrate the pile of the carpet. An office chair or the like having casters thereon, is then disposed on surface 16 so that the casters may move substantially unimpeded over sheet 12. Any lateral forces applied to the sheet will have no effect on the same with respect to movement thereof inasmuch as the frictional forces between the teeth and the pile will generally be too great to allow movement of the sheet over the carpet. Hence, sheet 12 is thus precluded from lateral shifting movement which would require frequent repositioning of the same, cannot in any way damage the adjacent supporting members of the desk or other proximal furniture, and is not subject to transverse bowing which would present a safety hazard as well as make the mat more subject to displacement.

The dispositions of devices 20 in the manner illustrated in FIG. 1, assures that the peripheral edges of the sheet will remain in relatively close proximity to the carpet at all times. This is particularly accomplished by placement of devices 20 adjacent to the center of the sheet inasmuch as the casters of an office chair or the like, normally engage surface 16 at locations between the peripheral edge of sheet 12 and locations of devices 20 with respect to the center of the sheet. Any movements of the casters to one side of the sheet or the other thus do not cause the peripheral edges to raise with respect to the carpet. Hence, the peripheral edges present a minimum projection upwardly from the pile of the carpet.

The thickness of base 22 of each device 20 is kept to a minimum so that sheet 12 will be relatively close to the upper surface of the carpet at all times. Thus, the tendency for sheet 12 to bow in the regions between devices 20 is substantially eliminated.

The embodiment of the invention illustrated in FIG. 2 is substantially identical with that illustrated in FIG. 1 except for the disposition of devices 20 on the lower surface 14 thereof. In FIG. 2, protector 10 has a number of devices 20 adjacent to the peripheral edge of sheet 12— specifically, adjacent to the four comers of the sheet. Also, a pair of devices 20 are adjacent to the center of the sheet to prevent bowing of the same as an article of furniture is supported thereon. In certain instances, it is convenient and desirable to position devices 20 in the manner illustrated in FIG. 2, especially where there is a relatively high probability that lateral forces will be applied to the sheet adjacent to the corners thereof. One or more devices 20 may be secured to projection 18 if desired, and such devices would serve to eliminate any lateral movements of sheet 12 due to the application of lateral forces to projection 18.

Protector 10 provides an effective means for supporting an office chair having casters thereon without damaging a carpet while at the same time being extremely resistant to shifting thereon and assuring that a smooth, hard surface will be provided for the casters of the article for all normal operative positions of the article itself.