Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to a chair with backward and forward tilt capabilities and more particularly, to a synchronous office chair with passive backward and forward tilt capabilities, which chair is simply constructed, reliable and relatively inexpensive.
2. Description of the Related Art
Many chairs, particularly office chairs, have weight activated backward tilt. By this it is meant that a user shifting his or her weight is able to tilt the back portion of the chair to a reclining position. When the user shifts his/her weight back to an upright posture, or when the user departs, the chair returns to its neutral position on its own. This phenomenon is often described as being “passive”. When the user shifts his/her weight forward, a spring returns the back portion of the chair to its upright position. Some office chairs are arranged so that the seat portion also moves in response to tilting of the back portion and is commonly referred to as being synchronous. Sometimes the seat portion is fixed to the back portion so that they pivot about the same angle and in other chairs the seat portion is arranged to be lowered or raised at a different rate than the rate of decline of the back portion resulting in different angular movements of the back portion and the seat portion.
What is described here is a chair having synchronous movement of back and seat assemblies with backward and forward passive tilt capabilities comprising a chair having a seat assembly, a back assembly, a frame assembly for supporting the seat assembly and the back assembly, a base and a pedestal mounted to the base and connected to the frame assembly, a first link operatively connected to the back assembly, to the frame assembly and to a third link, a first pivot connected to the frame assembly and to the first link wherein the first link is pivotal relative to the frame assembly, a second pivot connected to the first link and to the seat assembly, a second link operatively connected to the frame assembly and to a third link, a third pivot connecting the frame assembly and the second link, a third link operatively connected to the seat assembly and to the second link, a fourth pivot connected to the second link and to the third link, and a biasing member mounted to the frame assembly and being deformable upon tilting of the chair.
There are a number of advantages, features and objects achieved with the present invention which are believed not to be available in earlier related devices. For example, one advantage is that the present invention provides for a synchronous chair apparatus that is arranged to allow both passive forward and passive backward tilting of the chair. Other objects of the present invention are the provision of a chair with forward and backward tilt capabilities which is simply constructed and reliable. Further advantages of the present invention are that the backward and forward tilt chair described here is relatively inexpensive, easy to construct and efficient to assemble.
Yet another advantage of the passive chair is that tilting movement of the chair is derived from a user's shifting of his/her body weight and the chair moves in a synchronous fashion, namely tilting of the back assembly causes a pivot of the seat assembly but at a different rate.
A more complete understanding of the present invention and other objects, advantages and features thereof will be gained from a consideration of the following description of preferred embodiments read in conjunction with the accompanying drawing provided herein. The preferred embodiments represent examples of the invention which is described here in compliance with Title 35 U.S.C. section 112 (first paragraph), but the invention itself is defined by the attached claims.
While the present invention is open to various modifications and alternative constructions, the preferred embodiment shown in the various figures of the drawing will be described herein in detail. It is understood, however, that there is no intention to limit the invention to the particular embodiment, form or example which is disclosed here. On the contrary, the intention is to cover all modifications, equivalent structures and methods, and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims, pursuant to Title 35 U.S.C. section 112 (second paragraph).
Referring now to
The office chair operates in the usual fashion in that the back assembly may be tilted or reclined, and the frame assembly may be vertically adjusted so as to allow a user to select a comfortable height for the seat assembly. The chair also provides for synchronous movement of the back and seat assemblies. Thus, when a chair user leans rearwardly, not only does the back assembly recline, but the seat assembly also pivots in a predetermined relationship. The inventive chair disclosed here also passively tilts rearwardly and forwardly.
Reference is made to co-pending patent applications assigned to the same assignee as the present application and entitled Horizontally Adjustable Chair Armrest, application Ser. No. ______, filed ______(Docket No. 087522-785329); Chair Back, application Ser. No. ______, filed ______(Docket No. 087522-785336); Vertically Adjustable Chair Armrest, application Ser. No. ______, filed ______(Docket No. 087522-785347); Chair With Adjustable Seat Back, application Ser. No. ______, filed ______(Docket No. 087522-785350). These applications disclose other features of the chair. All disclosures of the Applications just mentioned are incorporated herein by reference.
The mechanism for allowing the chair 10 to tilt rearwardly as well as forwardly in an efficient manner will be best understood by reference to
A first pin 80 forms a first pivot and pivotally connects the mid-portion of the first link 50 to the frame 16. Another pin 82 forms a second pivot and pivotally connects the seat assembly 14 to the first link 50. A third pin 84 forms a third pivot and pivotally connects the frame assembly 16 and the one end portion 64 of the second link 62. A fourth pin 86 forms a fourth pivot and pivotally connects the one end portion 70 of the third link 68 to the other end portion 66 of the second link 62. The first pivot pin 80 is located more rearwardly and upwardly than the second, third and fourth pivot pins 82, 84, 86, the second pivot pin 82 is located more rearwardly and upwardly than the third and fourth pivot pins 84, 86 and the third pivot pin 84 is located more rearwardly and upwardly than the fourth pivot pin 86.
The mechanism also includes a biasing member in the form of a rubber block 90,
The second link includes spaced parallel bars (
It will be understood that other energy generating devices may be used, such as a leaf spring, a torsion spring or the like. Rubber or rubberlike material is preferred however because of rubber's damping characteristics, its ease of attachment to the chair, its noiselessness and its ability to sustain large deformations because it is highly elastic. Rubber also has the advantages of durability and high energy relative to size or volume. Thus, the block is compact.
A first end portion 92 of the resilient block 90 is attached to a fixed bracket 94 which is attached to the frame assembly 16 and the other end portion 96 of the resilient block is connected to a bracket 97 which is connected to the third link 68. When the second and third links move in response to rearward or forward tilt of the back assembly and synchronous movement of the seat assembly due to a chair user shifting his/her weight in the chair, the resilient block is deformed thereby setting up a biasing force seeking to return the block to its unstressed, neutral position. When a user moves back against the back assembly, the block distorts as shown in
To better understand the operation of the office chair, it should be understood that the frame assembly 16 is stationary in use after being adjusted vertically to the comfort of a specific chair user. The first pivot pin 80 and the third pivot pin 84 which are mounted to the frame assembly to allow rotation of other elements but they themselves remain in fixed locations. The second pivot pin 82 and the fourth pivot pin 86, however, are arranged so that they each move in an arc in response to movement of the links to which they are attached.
Movement of the links and pivot pins causes the resilient block to deform or bend and thereby to distort as diagrammatically shown in
The passive tilting may be appreciated by reference to
Referring to
In the reclined position shown in
In an analogous manner a user may lean forward in the chair, for example, while performing a computer task or writing or reading at a desk or other work surface. The forward tilt of the chair is shown in
The forward tilt causes the resilient block to deform downwardly as shown in
Referring now to
When the back assembly is reclined (
When the chair is tilted forward (
The kinematic figures also show the synchronous movement of the chair. For example, a counterclockwise pivot of the back assembly of about twenty degrees, induces a synchronous pivot of about 1.2 degrees in the seat assembly. Similarly, a clockwise pivot of the back assembly by about six degrees induces a synchronous pivot of about two degrees in the seat assembly.
The preferred distance between the first and second pivot pins 80, 82 is about 2.25 inches and the distance between the third and fourth pivot pins 84, 86 is about 2.0 inches. In the neutral position, the first pivot pin 80 is about 0.50 inches above and 2.17 inches behind the second pivot pin 82, about 5.66 inches above and 3.58 inches behind the third pivot pin 84 and about 6.45 inches above and 5.42 inches behind the fourth pivot pin 86. The angle of the first link 50 is about fifteen degrees from a horizontal reference line and the angle of the second link 62 is about 23.2 degrees from a horizontal reference line.
In a full reclined position, the first pivot pin 80 is about the same height and 2.25 inches behind the second pivot pin 82, about 5.66 inches above and 3.58 inches behind the third pivot pin 84, and about 5.66 inches above and 5.58 inches behind the fourth pivot pin 86. The angle of the first link 50 is about zero degrees from a horizontal reference line and the angle of the second link 62 is also about zero degrees from a horizontal reference line.
In full forward tilt, the first pivot pin 80 is about 0.99 inches above and 2.02 inches behind the second pivot pin 82, about 5.66 inches above and 3.58 inches behind the third pivot pin 84, and about 6.93 inches above and 5.13 inches behind the fourth pivot pin 86. The angle of the first link 50 is about twenty six degrees from a horizontal reference line and the second link 62 is about 39.2 degrees from a horizontal reference line.
In operation of the chair, a neutral position is assumed by the chair when there are no distortions of the resilient block and thereby no biasing force induced into the chair mechanism. To recline, a user merely shifts his/her weight rearwardly causing the resilient block to be deformed as shown in
The above specification describes in detail a preferred embodiment of the present invention. Other examples, embodiments, modifications and variations will, under both the literal claim language and the doctrine of equivalents, come within the scope of the invention defined by the appended claims. For example, the shape or design of the seat assembly and the back assembly may change and the chair will still be considered an equivalent structure. The length and location of the links and the locations of the pivot pins may also change somewhat and the chair will still be considered an equivalent structure and will still come within the literal language of the broadest claims even if angles and rises are somewhat altered. Yet other alternatives will also be equivalent as will many new technologies. There is no desire or intention here to limit in any way the application of the doctrine of equivalents nor to limit or restrict the scope of the invention.