Beds – Support for users body or part thereof – Removable support specially adapted for seating
Reexamination Certificate
2002-06-14
2004-02-10
Grosz, Alexander (Department: 3673)
Beds
Support for users body or part thereof
Removable support specially adapted for seating
C005S909000, C297S452420
Reexamination Certificate
active
06687933
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a body support system such as may be used for a seat cushion. More particularly, this invention relates to a body support system such as may be used for a seat cushion and having improved mechanical response characteristics and improved thermal interaction with a user.
The comfort provided to a user by a body support system such as a seat cushion will depend on a variety of factors. One such factor is the mechanical response of the body support system to the compressive and shear forces applied by a user interfacing the body support system, e.g., a user seated on a cushion. Mechanical response includes static and dynamic responses. Another such factor is the ability of the body support system to provide thermal regulation with a user resulting from the inherent heat exchange process/mechanisms in the body support system. If the body support system is to be used in conjunction with a moving vehicle/vessel/device including a wheelchair, a farm implement such as a tractor or riding mower, or as a seating element for public transportation, then the ability of the body support system to provide adequate dynamic response characteristics to applied dynamic excitations and reduce Whole Body Vibration (WBV) by means of reducing transmission of harmful frequency components to the user, is another factor.
Conventional contemporary office seats are usually made of either upholstered padding or synthetic mesh in a frame assembly. Each of these types of seats has its own characteristic thermal properties. Padded upholstery (e.g., polyurethane foam) seating provides limited heat exchange with the user, which however mainly occurs through conduction and sweat evaporation processes. As a result, upholstered padding is better suited for lower workspace temperatures on the order of 16-25° C. (61-77° F.) and shorter sitting times before heat starts to build up and un-evaporated sweat starts to develop at the user-body support system interface On the other hand, mesh seating provides excessive heat exchange between the surrounding environment and the user mainly through radiation and convection heat exchange processes. In the case of mesh seating, these heat exchange processes do not depend on intrinsic properties of the body support system, but also depend on extrinsic factors such as surrounding environmental parameters including temperature and air speed, and on factors such as workspace configuration, surface orientations, and temperatures and thermal reflectivity of adjacent surfaces such as floor and walls. As a result, mesh chairs may be better suited for higher workspace temperatures of 25-35° C. (77-95° F. and longer sitting times. Neither of these prior art seating designs provides for thermal regulation in a wide variety of office temperature environments and workspace configurations.
Another disadvantage of mesh seat upholstery is its tendency to “creep,” that is, to deform viscously or irrecoverably, with disproportional stress-strain rate characteristics especially in the territrial stress-strain regime, which might be reached (for many mesh materials)when the user's weight is large, therefore resulting in non-uniform mechanical response to a wide range of users. Creep is a significant problem when the seat mesh is subjected to heavy sustained user's weight over prolonged time. Control of creep usually requires cross directional mesh reinforcement with fibers that have very limited creep characteristics. Without proper control, however, creep can cause excessive deformation in the seat mesh, eventually leading to loss of contact at the user-seat interface, and a severe reduction in the total load carrying capacity of the body support system. This results in excessive cognitive (conscious and sub-conscious) weight shifting towards the front under-thighs and to the feet- and armrests, factors that may be directly related to discomfort and unfavorable ergonomic conditions.
Thermal properties are major ergonomic features that should be considered in the design of an office chair. The human body always works to retain its core temperature near 37° C. (98.6° F.), by means such as postural adjustments, varying skin temperatures such as by perspiration, regulation of cardiovascular and pulmonary activity such as pulse and breath rates to affect blood flow and vessel sizes especially in skin areas close to a heat-exchanging interface such as that with a seat cushion. A chair that prompts sweating after a relatively short period of sitting and which requires the human body to engage in such thermal self-regulatory processes will be uncomfortable and may affect work efficiency/productivity. For example, with conventional upholstered padding, heat can quickly build up at the user/seat interface causing the user to limit metabolic rates such as muscular activity to reduce heat generation, therefore severely affecting work efficiency. The user may also begin sweating to initially expedite the thermal transfer across the user skin, and to attempt to prompt the sweat evaporation cooling process. When the user/seat interface inhibits sweat evaporation due to low cushion vapor permeability under even small pressures, heat is not dissipated at the interface leading to even greater discomfort for the user. On the other hand, mesh chairs have high vapor permeability and heat dissipation and do not allow for any heat build up at the seat user interface. With colder workspace environments, and closer, oppositely oriented, highly reflective, and cold office space surfaces (floors/walls, etc.), and with high (transient or steady) airspeeds, the user is set to become responsible to generate heat that seeks thermal equilibrium with the whole environment; a condition that prompts discomfort. This might allow for excessive user heat loss or gain. It is therefore postulated that a limited heat build up at the interface would be favorable to reverse the thermal gradient across the interface. Thus, with open mesh seats the thermal comfort of the user becomes significantly dependent on the ambient temperature of the work environment and configuration.
Further, conventional seating designs do not provide for variations in the size and comfort levels of different users. Different individuals will have different load characteristics and different thermal generation rates therefore producing different comfort levels (including psychometrics).
It is thus one object of the invention to provide a body support system such as a seat cushion having improved thermal regulation properties.
It is yet another object of the invention to provide a body support system such as a seat cushion having improved mechanical response properties including wider low intensity pressure distribution and better dynamic response characteristics.
It is also another object of the invention to provide a an energy dissipation system as a component of the body of the support system to provide even greater comfort to a user.
It is still another object of the invention to provide a body support system such as a seat cushion in which the thermal regulation properties and/or the mechanical characteristics can be varied to the needs or preferences of a particular user or group of users by varying amongst the many design parameters in the system.
SUMMARY OF THE INVENTION
A body support system is provided having improved mechanical (static and dynamic) support characteristics and improved thermal interaction with a user. The improved static support is provided by means for distributing the weight of a user in response to applied compressive and shear forces at the user-support system interface. The means for distributing the weight of the user comprises a plurality of vertical columns disposed substantially centrally in said body support system. Without connecting the columns by means of an elastomeric layer, the columns are capable of deflecting substantially independently of one another in response to the compressive forces applied by a user. The improved thermal interaction is provided by st
Habboub Amin K.
Koepke Marcus C.
Phillips Matthew J.
Grosz Alexander
Hon Technology Inc.
Jones Day
Sandler Ronald A.
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