US5314240A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shell structure for use with a chair having synchronously moving seat and seat back
Assignee: Itoki Co Ltd
•
Filing: 1991-12-27
•
Granted: 1994-05-24
•
Expires: 2011-12-27
Abstract
Abstract A shell for a chair in which a bottom shell structure and a backrest shell structure are connected to supporting frame members such that when a light load is applied to the separate backrest shell the backrest shell will bend to accommodate the load, whereas when a heavy load is applied to the backrest shell the backrest bends and the supporting bars rock backwards. The bottom shell structure has a bottom portion and a partial backrest portion which are integrally formed on the same material and are connected by a curved portion with plural slots. Sideways notches are connected to the extreme left and right slots and extend toward the left and right edges of the shell structure. The edges of the shell adjacent the notches are curved into a U shape. This construction increases the flexibility of the curved portion, while maintaining a significant portion of the unslotted material strength. A separate shell structure is attached to supporting bars and forms the remainder of the backrest support. This separate shell structure has a jagged cross sectional shape where substantially parallel projections and recesses form grooves which extend the length of the backrest shell.
Inventors
- 👤 Yuji Ishi
- 👤 Toru Nagao
- 👤 Harumatsu Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:24
CPC Classifications
A; A47; A47C; A47C7/00; A47C7/36; A47C7/40; A47C7/405; A47C1/00; A47C1/02; A47C1/031; A47C1/032; A47C1/03255; A47C1/03261; A47C1/03272; A47C1/03277; A47C3/00; A47C3/12; A47C1/03274; Y; Y10; Y10S; Y10S297/00; Y10S297/02
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
A shell structure for use with a chair having a synchronously moving seat and seat back, the shell structure for the seat comprising: a bottom portion and a back portion of the same material, with a curved connecting portion therebetween; said curved connecting portion having at least two slots extending between said bottom portion and said back portion, wherein a portion of said curved connecting portion sandwiched between said slots has a greater curvature than other portions of said curved connecting portion; sideways notches extending outwardly from the outermost ones of said slots adjacent said bottom portion; and U-shaped bent portions extending out of the plane of said curved connecting portion and outwardly from said notches.
Claim 2
Dependent Claim
116 words
A shell structure for use with a chair having a synchronously moving seat and seat back, the shell structure for the seat comprising: a bottom portion and a back portion of the same material, with a curved connecting portion therebetween; said curved connecting portion having at least two slots extending between said bottom portion and said back portion, wherein a portion of said curved connecting portion sandwiched between said slots has a greater curvature than other portions of said curved connecting portion; sideways notches extending outwardly from the outermost ones of said slots adjacent said bottom portion; and U-shaped bent portions extending out of the plane of said curved connecting portion and outwardly from said notches.
Claim 3
Dependent Claim
28 words
A shell structure according to claim 1 wherein the rigidity of the center of said bottom portion is more than that of other portions of said bottom portion.
Claim 4
Dependent Claim
35 words
A shell structure for a backrest according to claim 1, wherein said shell structure comprises at least one of the materials selected from the group consisting of nylon, polypropylene, synthetic resin, and a light metal.
Claim 5
Dependent Claim
29 words
A shell structure according to claim 1, wherein the elasticity of a front edge of said bottom portion is more than that of other portions of said bottom portion.
Claim 6
Dependent Claim
28 words
A shell structure according to claim 4 wherein the rigidity of the center of said bottom portion is more than that of other portions of said bottom portion.
Claim 7
Dependent Claim
142 words
A shell structure for a chair having a seat and a seat back comprising: a seat shell having a bottom portion and a back portion connected by a curved portion; said curved portion having plural slots therein extending between said bottom portion and said back portion; a notched portion extending generally perpendicularly from each of the outermost ones of said plural slots; a U-shaped bent portion extending outwardly from each said notched portion and out of the plane of said curved portion for increasing the flexibility of said curved portion while maintaining the strength of said curved portion; and a seat back shell having generally parallel grooves therein, said grooves extending generally vertically when said seat back shell is attached to the chair, said grooves being shallower in a lower portion of said seat back shell than in an upper portion thereof.
Claim 8
Dependent Claim
142 words
A shell structure for a chair having a seat and a seat back comprising: a seat shell having a bottom portion and a back portion connected by a curved portion; said curved portion having plural slots therein extending between said bottom portion and said back portion; a notched portion extending generally perpendicularly from each of the outermost ones of said plural slots; a U-shaped bent portion extending outwardly from each said notched portion and out of the plane of said curved portion for increasing the flexibility of said curved portion while maintaining the strength of said curved portion; and a seat back shell having generally parallel grooves therein, said grooves extending generally vertically when said seat back shell is attached to the chair, said grooves being shallower in a lower portion of said seat back shell than in an upper portion thereof.
Claim 9
Dependent Claim
19 words
The shell structure of claim 6 wherein said seat back shell has an outer periphery that is generally flat.
Claim 10
Dependent Claim
24 words
The shell structure of claim 6 wherein said curved portion comprises portions between said slots that have a greater curvature than other portions thereof.
References Cited (Backward Citations)
US3669496A
Cited
US3734561A
Cited
US4123105A
Cited
DE2723722A1
Cited
US4368917A
Cited
US4418958A
Cited
US4556254A
Cited
US4498702A
Cited
US4660887A
Cited
US4856846A
Cited
US4776633A
Cited
US4892356A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-23 | 1997-11-22 | 1998-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-23 | 2001-11-22 | 2002-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-23 | 2005-11-22 | 2006-05-24 | $7700.00 | Window Closed / Lapsed |